How WACC blends the cost of equity and debt
Every company is financed by some mix of equity and debt, and each source has its own price. Shareholders expect a return for the risk of owning the business — often estimated with theCAPM calculator — while lenders charge interest. WACC combines those two prices into one figure by weighting each by its share of total capital, then knocking the tax shield off the debt side. Because it represents the minimum return the firm must earn to keep all of its investors whole, WACC is the natural discount rate for valuing future cash flows in aDCF calculator.
The WACC formula
WACC = (E/V)·Re + (D/V)·Rd·(1 − Tc)
where E = market value of equity, D = market value of debt, V = E + D (total capital), Re = cost of equity,Rd = cost of debt, and Tc = corporate tax rate. The term (1 − Tc) turns the headline cost of debt into its after-tax cost, capturing the tax-deductibility of interest.
What makes this calculator different
- It shows the weights. The equity weight (E/V) and debt weight (D/V) are calculated and displayed, so you can see exactly how the financing mix tilts the blend rather than just trusting a final number.
- The after-tax cost of debt, spelled out. The raw cost of debt and the tax-shielded figure Rd·(1 − Tc) are shown side by side, making the value of the tax deduction concrete.
- Each side’s contribution to the blend. The equity contribution (E/V)·Re and the debt contribution (D/V)·Rd·(1 − Tc) are broken out separately, so you can read off how much of the total WACC comes from each source.
Frequently asked questions
What is WACC?+
WACC stands for Weighted Average Cost of Capital — the blended rate a company pays to finance its assets across both equity and debt. The formula is WACC = (E/V)·Re + (D/V)·Rd·(1 − Tc), where E and D are the market values of equity and debt, V = E + D is the total, Re is the cost of equity, Rd is the cost of debt, and Tc is the corporate tax rate. Each source of capital is weighted by its share of the financing mix, so a firm funded mostly by equity will see its WACC dominated by the cost of equity. The result is a single number that represents the minimum return the company must earn to satisfy all of its investors.
Why is the cost of debt multiplied by (1 − tax rate)?+
Interest payments are tax-deductible in most jurisdictions, so borrowing reduces a company’s taxable income. That deduction lowers the effective cost of carrying debt — an effect known as the tax shield. If a firm pays 6% on its debt and faces a 25% tax rate, the after-tax cost is only 6% × (1 − 0.25) = 4.5%. The (1 − Tc) factor captures this benefit, which is why debt financing often looks cheaper than its headline interest rate suggests. Equity has no equivalent shield, since dividends are paid out of after-tax profits.
Why is debt usually cheaper than equity?+
Debt is typically cheaper for two reasons. First, lenders rank ahead of shareholders in the capital structure: if a company is liquidated, debt holders are repaid before equity holders see anything, so they bear less risk and demand a lower return. Second, the interest on debt earns the tax shield described above, lowering its after-tax cost further. Equity investors, by contrast, sit at the back of the queue and are compensated for that risk with a higher expected return. This is why adding a modest amount of debt can pull a company’s overall WACC down.
What is WACC used for?+
WACC is most commonly used as the discount rate in a discounted-cash-flow (DCF) valuation, where future free cash flows are discounted back to present value at the firm’s cost of capital. It also serves as a hurdle rate for capital budgeting: a project that returns more than the WACC creates value, while one that returns less destroys it. Because it reflects the blended expectations of all investors, WACC is a natural benchmark for whether an investment is worth making. Analysts also use it to compare the relative attractiveness of different financing decisions.
Does more debt always lower WACC?+
No — only up to a point. Initially, swapping expensive equity for cheaper, tax-shielded debt does pull WACC down. But as leverage rises, the probability of financial distress increases: lenders demand higher interest to compensate for default risk, and equity holders demand more because their residual claim becomes riskier. Beyond an optimal level, these rising costs more than offset the tax shield and WACC starts to climb again. The relationship is roughly U-shaped, so there is a debt level that minimises WACC rather than a "more is always better" rule.
Disclaimer: This calculator is foreducation and illustration only. WACC depends on estimates — the cost of equity, the cost of debt, and the right capital weights are all judgement calls, and small changes in inputs move the result. Its output is not a valuation or a recommendation, and nothing here is investment, tax, or trading advice.