All calculators

Project the growth of savings and investments with inflation-adjusted (real) returns, fees, taxes, contribution step-ups, and a full year-by-year breakdown.

Find how much to set aside each month to hit a target by a deadline — or how long your current pace will take.

CAGR, total return, and the true money-weighted return (IRR) when you add contributions — plus the inflation-adjusted real return.

Project dividend income with reinvestment (DRIP), rising payouts, and yield-on-cost — and see how much DRIP adds over taking cash.

The exact trades to hit your target allocation — plus a no-sell, contributions-only mode that rebalances without triggering taxable sales.

Compare two expense ratios side by side and see the dollars — and the share of your gains — that fees quietly consume over time.

Maturity value and interest from a certificate of deposit — plus what an early-withdrawal penalty would actually cost you.

Grow a savings balance at a real APY — and see what tax on interest and inflation leave you with in today’s money.

RSU value at vest, sell-to-cover shares, and the 22% withholding gap that leaves higher earners owing more at tax time.

The true investment yield on a T-bill (not just the quoted discount yield), the APY, and its state-tax-free advantage.

Your ESPP discount and lookback turned into a real return — the immediate gain and the eye-opening annualized rate.

Turn a nominal rate into its true APY, compare APY across compounding frequencies, and see the real dollars earned.

Simple and compound interest side by side — the total interest each way, the final balance, and exactly how many dollars compounding adds on top.

What a lump sum and regular contributions grow to at any rate and compounding frequency — with the split between what you put in and the interest you earn.

What a future lump sum or stream of payments is worth in today’s money once discounted — and how much value is lost to time at a given rate.

The compound annual growth rate that links a starting and ending value over time — the single rate that makes investments of different lengths comparable.

Future value with continuous compounding (P·e^(rt)), the effective annual rate it produces, and how much it beats compounding just once a year.

PVIFA — the present value interest factor of an annuity, the multiplier turning equal payments into one present value, behind loan and bond pricing

Sinking fund payment — the recurring deposit needed to hit a target amount by a future date, with the interest the compounding does for you

Growing annuity present value — payments rising at a constant rate each period — for inflation-linked income, escalating leases, or growing dividends

Your total return on an investment — capital gain plus income as a percentage of what you paid — split into the price return and the income return.

Fisher equation — convert nominal and real rates exactly, (1 + nominal) = (1 + real)(1 + inflation), not the nominal-minus-inflation shortcut

Return on investment from what you put in and got back — plus annualized (compound) ROI, the only fair way to compare different holding periods

Rule of 72 — how many years money takes to double at a given return, with the exact logarithmic answer to see how close the shortcut really is

Your weighted average cost per share across multiple buys — the true break-even price when you average down or build a position in stages.

Profit or loss on a stock trade after buy and sell commissions, with your return on cost as a percentage — the honest figure once fees are counted.

The dividend yield on a stock from its annual dividend and share price — the income return that lets you compare payouts across very differently priced shares.

The share of your income you actually save — the single number that, more than any return, decides how fast you reach financial independence.

HSA growth with the triple tax advantage quantified — the upfront deduction, FICA savings via payroll, tax-free growth, and the gap versus the same dollars in a taxable account.

Projects a 529 balance against the inflated future cost of college — the funding gap, and the monthly contribution that closes it, with education inflation modeled separately.

Solves exactly how long until your savings first cross $1,000,000 — the arrival date, your age that day, and how much of the million is contributions versus compounding.

Splits a lump sum across staggered CD rungs — each rung's maturity value at your entered APYs, the blended yield, and the cash-available timeline that laddering buys you.

Payment, total interest, and payoff timeline for any fixed-rate loan, with an amortization breakdown.

The monthly payment on any fixed-rate loan — plus total interest, the true APR once fees are counted, and a full amortization schedule with extra-payment savings.

Business loan payment, total cost, and effective APR — origination fees folded in, with a full amortization schedule to compare offers honestly

See how long a fixed payment takes to clear your balance — and how the shrinking minimum-payment trap costs you years and thousands in interest.

Compare the snowball and avalanche strategies across all your debts — payoff order, total interest, and which one frees you sooner.

The real out-the-door cost — sales tax with the trade-in credit, fees, and the negative-equity timeline showing when you stop being underwater.

Whether a 0% balance transfer pays off once the fee and the go-to APR are counted — plus the payment to clear it before the promo ends.

Your front-end and back-end DTI, the lender qualification band you fall in, and how much debt headroom you have before 36% and 43%.

Pay off an existing loan faster — compare extra, biweekly, and lump-sum strategies, or solve the payment to be debt-free by a target date.

Standard repayment vs an income-driven plan based on your discretionary income — the lower payment and the long-term tradeoff.

A full month-by-month amortization schedule with the principal-vs-interest crossover, extra payments, and CSV export.

How much car you can responsibly afford using the 20/4/10 rule — counting insurance and fuel, not just the loan payment.

Payment and true cost of an SBA business loan, including the SBA guarantee fee and the long terms SBA financing allows.

Whether buying out your car lease is smart — the all-in buyout cost vs the car’s market value, and the equity it captures.

Turns a small-sounding fee into its true APR (often 400%+), models the rollover trap, and compares the cost to safer credit.

The true cost of a credit-card cash advance — the fee, the higher APR, and the no-grace-period interest that starts on day one.

Convert a car lease money factor to its equivalent APR (and back) — multiply by 2400 — so you can compare lease financing against a loan on equal terms.

The low monthly payment during an interest-only period — and the jump to a full principal-and-interest payment when it ends, so the payment shock is no surprise.

The true APR on a loan once upfront fees are counted — always higher than the note rate — the apples-to-apples number for comparing loan offers honestly.

How much you can borrow for a monthly payment you can afford — working backwards from the payment to the principal, with the total interest over the term.

Monthly payment and the lump-sum balloon due at maturity — the classic 30/5 structure priced year by year, with an interest-only mode and the full cost to the balloon date.

Whether a premium card's annual fee earns its keep — net value from rewards, honestly-valued perks, and amortized welcome bonus versus a no-fee card, with the break-even spend.

The balance-weighted blended rate across multiple debts — what consolidation must beat — including the federal student-loan rule that rounds the weighted average up to the nearest one-eighth percent.

Monthly payment, full amortization schedule, the true lifetime cost of interest, and how extra payments shorten your loan.

Whether refinancing pays off: the new payment, the break-even point on closing costs, and the term-reset interest trap.

How much house you can afford using real front-end and back-end DTI ratios — and which one is actually limiting your budget.

A true opportunity-cost comparison: invested down payment, appreciation, full ownership costs, and the year buying pulls ahead.

Your available credit from home equity, and the payment shock when the interest-only draw period flips to amortizing repayment.

Whether buying discount points pays off — the upfront cost, the lower payment, and the break-even month you must pass to win.

Your monthly PMI and the full cancellation timeline — the 80% point you can request it gone and the 78% automatic cutoff.

FHA payment with upfront and annual MIP — including the catch that with under 10% down, MIP never cancels for the life of the loan.

An itemized estimate of buyer closing costs — and the total cash to close you actually need to bring to the table.

Qualify a rental on its cash flow: the DSCR from rent and expenses, whether it clears the lender target, and the max loan it supports.

Prorated rent for a partial month by all three methods (actual days, 30-day, annualized) so you can match your lease.

Cap rate on a rental property — net operating income over price, the unlevered yield used to value real estate — plus the implied NOI multiple

Net operating income — effective gross income after vacancy, less operating expenses, before mortgage and tax — the driver of cap rate and cash-on-cash

The pre-tax return on the actual cash you put into a rental — cash flow after the mortgage divided by money invested — the levered counterpart to the cap rate.

The price-to-gross-rent multiple — how many years of gross rent equal the purchase price — the fast back-of-envelope screen for shortlisting rental deals.

Gross and net rental yield on an investment property — annual rent as a percentage of value, before and after running costs — for comparing income across properties.

Your new rent after a percentage increase — the monthly bump and what it adds up to over a full year, so a “small” rise doesn’t catch you out.

The good-faith deposit on a home offer — a percentage of the purchase price, credited toward your down payment at closing, with notes on when it’s at risk.

Price per square foot from price and area — the great equaliser for comparing homes of different sizes against neighbourhood comps.

Monthly payment, total interest, and total cost on a land or lot loan — which typically carry higher rates and shorter terms than a home mortgage.

Half-payments every two weeks make 13 full payments a year — the interest saved and years cut, modeled both as a true biweekly schedule and as the extra-principal equivalent.

Recast, prepay, or do nothing — what a lump sum does to your mortgage under each path: the new recast payment, the interest saved, and which choice wins on cash flow vs total cost.

What a seller actually walks away with — sale price minus mortgage payoff, commission, closing costs, transfer tax, concessions, and prep, itemized as a seller net sheet.

Model contributions, employer match, and withdrawals to see whether your nest egg lasts through retirement.

Your financial-independence number, years to reach it, your Coast FIRE figure, and savings rate — all in today’s money.

After-tax retirement outcomes for Roth vs Traditional — including investing the up-front tax saving and your break-even tax rate.

Project your 401(k) with the real IRS contribution limits and catch-up — and see the employer match you’re leaving on the table.

Project tax-free Roth growth within the IRS contribution limits, and see exactly how much the tax-free growth beats a taxable account.

Required minimum distributions using the real IRS Uniform Lifetime Table, projected across every year with the estimated tax on each.

Estimate your benefit with the real PIA bend-point formula, and see how claiming from 62 to 70 changes your monthly check.

403(b) balance at retirement from your contribution rate, employer match, and expected return — the tax-deferred plan for school and non-profit staff

How long your savings last under inflation-indexed withdrawals — with the 4% rule amount and your starting withdrawal rate, so you can pressure-test a drawdown plan.

Pension lump sum vs the present value of the monthly pension — the payout rate and which option is worth more at your assumed return and lifespan

The age at which delaying Social Security overtakes claiming early — the lifetime crossover between a smaller check sooner and a larger one later.

The level monthly income a lump-sum premium buys over a fixed term — plus total payout and interest — for a period-certain immediate annuity.

Coast FIRE — whether you've saved enough that growth alone, with no further contributions, carries you to financial independence — and the gap to it

The smaller nest egg you need when part-time income covers part of your expenses — your Barista FIRE number, when you reach it, and how it compares with full FIRE.

How much of a backdoor Roth conversion is taxable under the IRS pro-rata rule — the exact Form 8606 line-by-line arithmetic, with the aggregation trap and the basis you carry forward.

Short- vs long-term tax compared, the dollar benefit of crossing the one-year mark, and your after-tax annualized return.

Estimate your 2025 federal income tax with a bracket-by-bracket breakdown, FICA, and your true marginal vs effective rate.

The 15.3% self-employment tax on your net earnings — Social Security and Medicare, both halves — with the 92.35% base and the deductible half worked out.

FICA tax withheld from your pay — the 6.2% Social Security and 1.45% Medicare rates, the wage-base cap, and the 0.9% high-earner surtax

Effective tax rate — the share of income you actually pay — and how far it sits below your marginal bracket, so a raise never costs you money

Add sales tax to a price or back it out of a receipt total — the correct way, dividing by one-plus-the-rate rather than just subtracting it.

Annual and monthly property tax from market value, assessment ratio, and tax rate — with the effective rate on what your home is really worth, and mills explained.

Lump sum vs annuity, after federal and state tax — compared on a present-value basis so you see which option really wins.

See why a large gift almost never triggers tax — the per-recipient annual exclusion and the lifetime exemption, explained.

Tax across multiple crypto disposals — short vs long-term, loss netting, and the reminder that crypto-to-crypto trades are taxable.

Powerball cash value vs the 30-year graduated annuity, after federal and state tax, compared on a present-value basis.

Mega Millions lump sum vs annuity after tax, with the 30 graduated payments and a present-value comparison.

Federal estate tax on what an estate leaves above the exemption, at the top rate — with the effective rate on the whole estate, and why most estates owe nothing.

Add value-added tax to a net price or back it out of a gross total — the correct way, dividing by one-plus-the-rate — for any VAT or GST percentage.

Salary converter — turn any pay rate (hourly, weekly, monthly, annual, and more) into every other frequency, using your real hours and weeks worked

Pay raise calculator — your new salary, the monthly increase, and the real, inflation-adjusted raise that shows whether buying power actually grew

Estimate net pay from gross — after FICA, income tax, and pre-tax deductions — as an annual, monthly, and biweekly figure, plus the share of gross you actually keep.

Bonus tax — what you take home after the flat 22% federal supplemental withholding, FICA, and state tax, and why that isn't your real tax bill

Total pay from base plus commission on your sales, with the share of your income that rides on performance — for any base-plus-commission or commission-only role.

The gross pay needed to net a target take-home amount — dividing by one-minus-the-rate, the right way to gross up a bonus or relocation payment.

Turn an hourly, weekly, or monthly rate into your true annual income, with your real hours and weeks worked factored in — not just a flat ×2,080.

Convert an annual salary into the equivalent hourly wage, adjusting for the hours and weeks you actually work so the rate reflects your real schedule.

See what your hourly wage adds up to over a full year — and at every pay period in between — based on the hours and weeks you work.

Work out your gross monthly income from any pay rate — useful for budgets and rent or loan applications that ask for a monthly figure.

Find your wage at any pay rate and frequency — hourly, daily, weekly, biweekly, monthly, or yearly — with your real hours and weeks worked built in.

Calculate your pay every two weeks (26 paychecks a year) from any rate — and see exactly how it differs from a twice-a-month semimonthly check.

Work out your twice-a-month paycheck (24 a year) from any pay rate — and see why it’s larger, but less frequent, than biweekly pay.

Turn any pay rate into your weekly gross pay — and see the monthly and annual equivalents alongside it.

What you actually earn per hour once commute time, unpaid work hours, and job costs are counted — and any purchase converted into the hours of life it costs.

The percentage change between two consecutive periods — the momentum metric behind analytics and KPI dashboards — with the absolute change alongside.

Find your gross margin from cost and price, or price a product to hit a target margin — with the markup, profit, and the margin-vs-markup distinction made clear.

Work out the markup on a product, or set a price from a target markup — and see why a markup is always a bigger number than the margin it produces.

Calculate gross profit margin from revenue and cost, see the dollar profit per unit, and price to a target margin — the number that protects your bottom line.

Convert between margin and markup and see both at once for any cost and price — so you never price off the wrong one and quietly lose profit.

Return on ad spend from revenue and ad cost — plus the full funnel (CPM, CPC, CTR, conversion rate, CPA, ROI) so you see what is really driving the number.

Cost per thousand impressions from spend and impressions — with CPC, CTR, conversion rate, CPA, ROAS, and ROI for the same campaign in one view.

Click-through rate from clicks and impressions — alongside the rest of the funnel so you can tell whether a high CTR is actually converting.

Your conversion rate from conversions and clicks — with cost per conversion, ROAS, and ROI so you know what each conversion costs and earns.

Your fully-loaded cost to acquire a customer — every sales and marketing dollar divided by the customers it won, the foundation of healthy unit economics.

Customer lifetime value from ARPU, margin, and churn — plus the LTV:CAC ratio and CAC payback period that reveal whether growth actually pays

The share of customers lost over a period, with its retention complement — the leak in the bucket that quietly compounds and sets the ceiling on lifetime value.

How many of the customers you started with are still here — new sign-ups stripped out, so growth can’t hide a leaky base. The quiet engine of compounding revenue.

The cost of a single conversion — lead, sign-up, or sale — at the campaign level, and how it differs from the fully-loaded CAC for a paying customer.

Break-even point — the units and revenue needed to cover costs, fixed costs divided by contribution margin per unit — the first number a business needs

The contribution margin per unit and its ratio — what each sale leaves toward fixed costs and profit after variable costs — the engine behind break-even and pricing.

Gross and net profit from revenue, cost of goods sold, and operating expenses — with the gross and net margins that show how much of each sales dollar you keep.

The order size that minimizes total inventory cost — balancing ordering against holding costs — plus how often to order and the annual cost at that quantity.

How long an investment takes to pay for itself — initial outlay divided by annual cash flow — the quick screen for whether a project recovers its cost soon enough.

All three textbook forms of customer lifetime value — simple, margin, and the discounted Gupta–Lehmann perpetuity — with the LTV:CAC ratio and CAC payback months.

Full depreciation schedules under straight-line, double-declining balance, sum-of-the-years-digits, and units of production — year by year, with book value tracked to salvage.

Gross burn, net burn, and months of runway — with a growth simulation that answers the default-alive question: does revenue reach break-even before the cash runs out?

Current, quick (acid-test), and cash ratios plus net working capital from a handful of balance-sheet lines — the three liquidity tests side by side with interpretation bands.

The fully-loaded annual cost of an employee — salary plus employer FICA, unemployment taxes, benefits, and overhead — with the cost multiplier and true cost per working or billable hour.

Options pricing with the Black-Scholes-Merton model — live Greeks, an implied-volatility solver, and payoff at expiry, worked step by step

Binomial option pricing on a Cox-Ross-Rubinstein lattice — European and American, converging to Black-Scholes, with the early-exercise premium

Monte Carlo option pricing — simulate thousands of random price paths, watch the estimate converge to Black-Scholes, and see the standard error shrink

CAPM expected return — risk-free rate plus beta times the equity risk premium — the return an investment should earn for its market risk

Dividend discount model value from D₁ ÷ (r − g) — the Gordon Growth present value of all future dividends, and why the r − g spread dominates

DCF intrinsic value — projected free cash flows plus a terminal value discounted to today, with how much rests on the terminal assumption

Compute the weighted average cost of capital — the blend of the cost of equity and the after-tax cost of debt by their weights — the discount rate that powers a DCF.

Bond price from yield, or yield to maturity from a market price — with the premium/discount, current yield, and the cash flows behind the number

Sharpe ratio — excess return over the risk-free rate per unit of volatility — the standard measure of risk-adjusted return, shown step by step

Forward and futures pricing by cost-of-carry — spot grown by financing and storage, less income — and whether the market is in contango or backwardation

Option strategy payoff at expiry for spreads, straddles, covered calls, and iron condors — Black-Scholes-priced legs, break-evens, max profit and loss

Option Greeks charted across the underlying price — delta, gamma, vega, theta, and rho, and how they shift as spot moves toward the strike

Bond duration and convexity — Macaulay and modified duration, and how the two together estimate a price change far better than duration alone

Net present value of a cash-flow series at your discount rate — per-period discounting, the profitability index, and a clear accept/reject signal

Internal rate of return — the discount rate at which NPV is zero — solved numerically, with the NPV profile drawn so you can see where it crosses

Perpetuity present value — level or growing, C ÷ r or C ÷ (r − g) — the engine behind dividend-growth valuation and DCF terminal values

Sortino ratio — risk-adjusted return using downside deviation only, so upside volatility isn't penalised — shown side by side with Sharpe

Expected return — the probability-weighted average across scenarios, plus the variance and standard deviation that measure its risk

Market cap from share price and shares outstanding, with the mega/large/mid/small/micro-cap tier — the equity value the market puts on the company

Enterprise value — the true takeover cost: market cap plus debt, preferred, and minority interest, less cash — built from the balance sheet

P/E ratio from share price and EPS (or net income and shares), plus the earnings yield it implies — the most-quoted valuation multiple

PEG ratio — the P/E-to-growth measure that puts a high multiple in context: a 30× P/E is cheap if earnings grow 30% a year

EV/EBITDA — the enterprise multiple that values the whole business against its cash earnings, so debt-heavy and debt-free firms compare equally

P/B ratio comparing market price to accounting book value, with the premium or discount to book — most telling for asset-heavy firms like banks

Return on equity — net income as a percentage of shareholders' equity — the headline measure of the return a company earns on its owners' capital

Return on assets — profit as a percentage of everything the company owns — how efficiently the asset base becomes earnings, unflattered by leverage

Return on invested capital — NOPAT over the capital put to work — the truest test of operating quality, compared against the cost of capital

Return on capital employed — operating profit over long-term capital, assets minus current liabilities — a pre-tax measure for capital-intensive firms

Return on sales — operating income as a percentage of revenue — the margin that captures pricing power and cost control before financing and tax

DuPont analysis — decompose return on equity into profit margin, asset turnover, and financial leverage to see what really drives a company's ROE

Current yield — annual coupon income as a percentage of a bond's market price — and how it sits between the coupon rate and the yield to maturity

Coupon payment per period — face value times coupon rate, split by frequency — plus the annual income and total coupons over the bond's life

Coupon rate recovered from a bond's periodic payment and face value — the fixed rate set at issue that never changes with the market price

Bond equivalent yield — annualize a T-bill's discount yield on a 365-day year so it compares with coupon bonds, alongside the bank-discount quote

Tax-equivalent yield — the pre-tax yield a taxable bond must offer to match a tax-free municipal in your bracket, with a side-by-side check of which wins

Earnings per share — profit for common shareholders over shares outstanding, preferred dividends removed first — the base of the P/E and PEG ratios

EPS growth — total and annualized (compound) growth between two periods — the engine behind the PEG ratio and the test of a high multiple

Graham number — Benjamin Graham's ceiling for a defensive buy, √(22.5 × EPS × book value per share) — plus the margin of safety versus price

Intrinsic value per share via Graham's revised formula — EPS × (8.5 + 2g) discounted by the corporate bond yield — with the margin of safety

Net asset value per share — assets minus liabilities, divided by shares — the figure mutual funds price at, and the benchmark for discounts

Asset turnover — revenue divided by total assets — how efficiently assets become sales, the efficiency lever in the DuPont breakdown of ROE

Inventory turnover — how many times a year inventory is sold and replaced, COGS over average inventory — plus the days-inventory holding period

Receivables turnover — how quickly a company collects what it is owed, credit sales over average receivables — with days sales outstanding

EBITDA margin — core operating profitability before financing, tax, and depreciation — for comparing firms with different capital structures

Retention ratio — the share of earnings kept to reinvest, equal to one minus the dividend payout — the plowback input to sustainable growth

Sustainable growth rate — return on equity times the retention ratio — the fastest a company can grow without new equity or more leverage

Days payable outstanding — how long a company takes to pay suppliers, accounts payable over COGS — the third leg of the cash conversion cycle

Cash conversion cycle — days inventory plus days sales minus days payable — a negative cycle means suppliers are funding the business

Retained earnings rolled forward — beginning balance plus net income minus dividends — the running total of profits kept rather than paid out

The interest rate the yield curve implies for a future period, derived by no-arbitrage from two spot rates. Educational, not investment advice.

PVGO — the present value of growth opportunities: how much of a stock's price is growth expectation, price minus its no-growth earnings value

The Kelly criterion stake that maximizes long-run bankroll growth — full, half, and quarter Kelly with the expected growth rate at each, and a clear no-edge warning.

How volatility pulls compound returns below the average — arithmetic vs geometric mean from summary stats or a real return series, with the long-run dollar gap.

Yield to call on a callable bond — solved from price, call date, and call price by bisection — with the YTM comparison and the yield to worst brokers must quote.

All three free cash flows — simple FCF, cash flow to the firm, and cash flow to equity — with the reconciliation bridge between them and the discount rate each one pairs with.

Bankruptcy risk by the Altman Z-score — all three published variants with exact coefficients, the distress/grey/safe zones, and each ratio's contribution shown.

Jensen's alpha — the return a portfolio earned above its CAPM-required return — from the risk-free rate, beta, and market return, with the full benchmark breakdown.

Risk-adjusted return per unit of market (beta) risk — the Treynor ratio with a market-benchmark comparison, completing the Sharpe and Sortino performance trilogy.

Put-call parity — solve the missing call or put from the other three legs, or check all four quotes for a parity gap and which side is rich. European, no-dividend form.

Markowitz two-asset portfolio return and risk from weights, volatilities, and correlation — with the diversification benefit quantified and the minimum-variance weights solved.

Unlever a comparable firm's equity beta or relever it at a target capital structure with the Hamada equation — the workhorse step of every comps-based cost-of-equity estimate.

Backs the implied volatility out of an observed option price by inverting Black-Scholes — Newton-Raphson on vega with a bisection fallback, no-arbitrage bounds checked first, and the solver's working shown.

Price elasticity of demand by the midpoint (arc) or point method, with the elastic/inelastic classification and the total-revenue test worked out step by step.

Consumer surplus, producer surplus, and total gains from trade — from a market price and quantity, or by solving linear demand and supply curves for equilibrium.

Solve the deflator identity for nominal GDP, real GDP, or the deflator itself — and turn two deflators into the economy-wide inflation rate between them.

The Keynesian spending multiplier from MPC — spending, tax, and balanced-budget multipliers plus the round-by-round geometric series showing where the total GDP change comes from.

The money multiplier and the maximum money a deposit can support under fractional-reserve banking, with a round-by-round lending table and a fuller model adding currency drain and excess reserves.

Deadweight loss from a per-unit tax or observed price gap — the Harberger triangle, tax revenue, trades lost, and an optional elasticity-based split of who bears the burden.

Market concentration by the Herfindahl–Hirschman index — squared shares, the DOJ/FTC 2023 merger-guideline bands, the numbers equivalent, and the ΔHHI of a hypothetical merger.

The equation of exchange MV = PY solved for any variable, plus the growth-rate form that turns money growth into implied inflation — with the velocity caveats stated honestly.

Income inequality from a pasted list of incomes — the Gini coefficient by the sorted closed form, the Lorenz curve behind it, and the income shares of the top 10% and bottom 50%.

GDP growth as a simple, BEA-style annualized-quarterly, or average annual rate — the three headline conventions from the same two observations, with per-capita growth and rule-of-70 doubling time.

Marginal cost from a single cost change or a full cost schedule — per-unit MC, average total cost, marginal revenue, and the profit-maximizing output under the MR = MC rule.

The benchmark policy interest rate the Taylor rule prescribes from inflation and the output gap — with a term-by-term decomposition and a comparison against the actual rate.

Cross-price elasticity — are two goods substitutes or complements — and income elasticity with the normal, inferior, and luxury classification, by the midpoint or point method.

Translates an unemployment gap into an output gap (or GDP growth into a predicted unemployment change) using Okun's rule of thumb — with an adjustable coefficient, because it is an empirical regularity, not a constant.

Purchasing power in both directions, the cumulative erosion of a fixed sum, and the income you’d need to keep pace.

Map your real expenses into the 50/30/20 needs/wants/savings buckets, see which one you overspend, and find your savings rate.

How many months you’re covered today, a recommended 3–6 month target band, and how long it takes to get there at your pace.

Turn a mix of weekly, monthly, and yearly subscriptions into one true annual cost — and see what investing it instead would be worth.

Tip on the pre-tax subtotal (not the tax), split the bill any number of ways, round up, and compare common tip percentages.

Categorized assets and liabilities, your liquid vs illiquid split and debt-to-asset ratio, and a multi-year net-worth projection.

Compare two cities and find the salary you’d need to keep your standard of living — with a category-by-category breakdown.

Per-card and overall utilization against the 30%/10% guidance — plus the exact paydown to reach a target ratio.

How much coverage you need via the DIME method (debt, income, mortgage, education) — not a crude multiple of your income.

Split a wedding budget across categories using typical industry percentages, with the per-guest cost that drives the total.

Sale price and amount saved — including stacked discounts (which multiply, not add) and the real out-the-door price with tax.

Work out the sale price and dollars saved for any percent off — plus stacked "extra % off" coupons (which multiply, not add) and the final price with tax.

Turn a percentage discount into the price you actually pay and the amount you save — with support for a second stacked discount and sales tax.

Gross pay with time-and-a-half and double-time tiers, the overtime premium, and a weekly-to-annual breakdown.

Split your take-home pay into needs, wants, and savings on the 50/30/20 rule — a simple, flexible budget framework with the dollar targets worked out for you.

Fuel cost of a trip from distance, fuel economy, and price per gallon — plus cost per mile, to compare routes, vehicles, and the price of a commute

What an appliance costs to run — daily, monthly, and yearly — from its wattage, hours of use, and your price per kWh. Find the quiet energy hogs in your home.

Three percentage questions in one: what is X% of Y, X is what percent of Y, and the percentage change from one number to another — each with the working shown.