How a CD ladder works
CDs pose a dilemma: longer terms usually pay more, but they lock your money up, and breaking one early costs months of interest. Laddering dissolves the dilemma by holding every term at once. Split the money into equal rungs and buy CDs maturing at regular intervals — say 1, 2, 3, and 4 years. From day one, the long rungs earn near the long-term rate, yet a rung matures every year, handing you penalty-free cash to spend or reinvest. And the ladder improves with age: after the first cycle, each maturing rung rolls into a new CD at the longestterm, so in steady state every dollar earns the longest-term rate while the maturity schedule keeps ticking at the same interval. This calculator never assumes current market rates — you type in the APY each bank quotes you for each rung.
The formulas
MVₖ = deposit × (1 + APYₖ)^(mₖ ÷ 12), mₖ = k × spacing
weighted life = Σ(depositₖ × yearsₖ) ÷ total
blended APY = (ΣMV ÷ total)^(1 ÷ weighted life) − 1
where rung k holds deposit = total ÷ rungs and matures after mₖ months. APY is the effectiveannual yield, so each rung’s maturity value depends only on its APY and term. The blended APY is defined as the annualized return of the whole ladder over its dollar-weighted life — the single rate that would grow the full deposit into the sum of all maturity values over that average life. It is a summary statistic, not a quoted rate: because maturity values from different horizons are summed, it lands slightly above the per-rung APYs, which is why the simple average of your entered APYs is reported alongside it.
Worked example
Ladder $20,000 across 4 rungs spaced 1 yr apart, with user-entered APYs of 4.00%, 4.20%, 4.40%, 4.50% from shortest to longest rung:
| Step | Amount |
|---|---|
| Split $20,000 across 4 rungsequal deposits, one CD maturing every 1 yr | $5,000.00 each |
| Rung 1: 4.00% APY, matures at 1 yr$5,000.00 × (1 + 0.040)^1 — interest $200.00 | $5,200.00 |
| Rung 2: 4.20% APY, matures at 2 yrs$5,000.00 × (1 + 0.042)^2 — interest $428.82 | $5,428.82 |
| Rung 3: 4.40% APY, matures at 3 yrs$5,000.00 × (1 + 0.044)^3 — interest $689.47 | $5,689.47 |
| Rung 4: 4.50% APY, matures at 4 yrs$5,000.00 × (1 + 0.045)^4 — interest $962.59 | $5,962.59 |
| Total interest across the ladderall rungs together mature to $22,280.88 | $2,280.88 |
| = Blended APY of 4.41%($22,280.88 ÷ $20,000)^(1 ÷ 2.5 yr weighted life) − 1; simple average of the entered APYs is 4.28% | 4.41% |
Computed with this calculator's default settings — open the tool above and you'll see the same numbers, then swap in the APYs your banks actually quote.
Why ladder instead of buying one long CD
The single long CD is the yield-maximizing choice only if nothing goes wrong for its entire term. The ladder is the version of that bet a household can actually live with: liquidity arrives on a schedule, so an emergency costs at most one rung’s early-withdrawal penalty instead of the whole balance’s. It also diversifies reinvestment timing — with everything in one CD, your entire stake reprices on one date, at whatever rates happen to be that day; with a ladder, only a slice reprices at a time, averaging you into the rate environment. The cost of these benefits is visible right in this calculator: the shorter rungs typically carry lower APYs, which pulls the blended yield below what a single longest-term CD would quote — until the steady state, when every rung is a long CD.
Model a single rung in detail — including what breaking it early would cost — with ourCD calculator, translate a bank’s quoted rate and compounding into a true yield with theAPY calculator, or see how regular deposits grow outside a ladder with thesavings calculator.
Frequently asked questions
What is a CD ladder?
A CD ladder splits one lump of savings across several certificates of deposit with staggered maturity dates — for example, four equal CDs maturing at 1, 2, 3, and 4 years. Instead of choosing between a short CD (flexible but usually lower-yielding) and a long CD (higher-yielding but locked up), the ladder holds both at once. One rung matures at every interval, so cash surfaces regularly, while the longer rungs keep earning the longer-term rates. It is the standard structure for savers who want CD yields without freezing all their money for years.
How do I build a CD ladder with $20,000?
Divide the total evenly across the number of rungs — with four rungs, that is $5,000 per CD — then buy CDs with staggered terms: one 1-year, one 2-year, one 3-year, and one 4-year. Each rung earns whatever APY you can find for that term (this calculator lets you type in a separate APY per rung, since quoted rates change constantly). When the 1-year CD matures, you can reinvest that $5,000 into a new 4-year CD; a year later the original 2-year rung matures and rolls the same way. After the first cycle, every dollar sits in a 4-year CD, but one still matures annually.
Is a CD ladder better than one long CD?
A single long CD usually posts the highest quoted APY, and if you are certain you will not touch the money, it earns the most. The ladder trades a little yield for a lot of flexibility: only a fraction of your money is ever more than one spacing interval away from being penalty-free cash, so a surprise expense costs at most one rung’s early-withdrawal penalty rather than the whole balance’s. Laddering also spreads reinvestment across dates, so you are never rolling everything over on the single worst day for rates.
What happens when each rung matures?
At maturity the bank returns that rung’s principal plus interest, and you choose: take the cash, or reinvest. Most banks auto-renew a matured CD into a similar term unless you act during a short grace period (often about 10 days), so mark the dates. To keep the ladder running, the classic move is to reinvest each maturing rung into a new CD at the ladder’s longest term — that preserves the spacing while shifting every dollar to the term that typically pays most. If you need the cash instead, you simply let that rung retire and the ladder shrinks by one.
Are CDs FDIC insured?
Yes — CDs issued by an FDIC-member bank are deposit products, covered by federal deposit insurance up to the standard limit of $250,000 per depositor, per insured bank, per ownership category. Credit-union CDs (share certificates) carry equivalent NCUA coverage. A ladder spread across multiple banks can extend total coverage, since the limit applies at each institution separately. The insurance protects against bank failure, not against early-withdrawal penalties or the possibility that rates rise after you lock in. Check the FDIC’s official resources for the current rules and limits.
Sources
The official figures this page quotes are drawn from the primary sources above — check them (or a qualified professional) before relying on a result.
Disclaimer: This calculator is foreducation and illustration only. It uses the APYs you enter — it does not quote or track current CD rates — and assumes each rung is held to maturity with interest compounding at the stated APY. Real CDs differ by bank: minimums, grace periods, early-withdrawal penalties, and renewal terms all vary. Nothing here is investment, tax, or banking advice.