Definition
WACC blends two components — the cost of equity and the after-tax cost of debt — weighted by a company's actual mix of equity and debt financing. It represents the minimum return a business needs to generate across all its capital to satisfy both shareholders and lenders, and is used as the discount rate in a DCF valuation.
Formula
WACC must bail out when market cap is missing or effectively zero — without that guard, the formula collapses toward 100%-debt weighting and produces a nonsensical, artificially low WACC. Small changes in WACC produce outsized swings in a DCF's output, since the rate compounds over every projected year.
Cost of Debt (Kd)
The cost of debt is the effective interest rate a company pays on its borrowings — the second input WACC needs, alongside the cost of equity. It's calculated pre-tax first, then adjusted down for the interest tax shield before it goes into the WACC formula above.
After-tax cost of debt
This after-tax figure — not the raw pre-tax rate — is what actually goes into the WACC formula, since the interest tax shield lowers debt's real cost to the company. Using the pre-tax rate by mistake overstates WACC and understates a DCF's intrinsic value.
Worked example: cost of debt
Cost of Equity (Ke)
The cost of equity is the return shareholders require to hold the stock, given its risk — the first input WACC needs, alongside the cost of debt. Unlike debt, it has no observable market rate, so it is estimated with the Capital Asset Pricing Model (CAPM).
Worked example: cost of equity
Worked example
Worked example
WACC by sector — rough ranges
There is no single "correct" WACC — it depends on a company's capital structure, its beta, and the risk-free rate in its market. As a rough orientation, these are typical ranges seen in published estimates:
| Sector | Typical WACC range |
|---|---|
| Regulated utilities | 4–6% |
| Consumer staples, telecoms | 6–8% |
| Industrials, materials, energy | 8–10% |
| Technology, healthcare | 9–12% |
| Early-stage / high-growth | 12%+ |
Illustrative only. A utility sits low because regulated, predictable cash flows carry a low beta; an early-stage growth company sits high because its cash flows are uncertain and it often carries little debt, so it gets less benefit from the tax shield that lowers the blended rate.
Common mistakes
Frequently asked questions
What is the formula for the cost of debt in WACC?
Pre-tax cost of debt (Kd) = Interest Expense ÷ Total Debt. Because interest is tax-deductible, WACC uses the after-tax version: Kd × (1 − Tax Rate). For example, a 5% pre-tax rate at a 25% tax rate becomes 5% × 0.75 = 3.75%.
What is WACC in simple terms?
WACC is the blended minimum return a company has to earn across all the money invested in it — both shareholder equity and borrowed debt — to keep both groups satisfied. It is used as the discount rate in a DCF: future cash flows are worth less today, and WACC is the rate that discounts them back.
Why is the after-tax cost of debt used in WACC instead of the pre-tax rate?
Interest payments reduce a company's taxable income, so a dollar of interest costs the company less than a dollar after tax — the interest tax shield. WACC reflects the real economic cost, so it uses Kd × (1 − tax rate). Using the pre-tax rate overstates WACC and understates the resulting valuation.
How do you calculate WACC from a balance sheet and income statement?
Market value of equity (E) comes from share price × shares outstanding, not the balance sheet. Total debt (D) comes from the balance sheet — short-term plus long-term borrowings. Interest expense and the effective tax rate come from the income statement. Cost of equity is estimated separately via CAPM using beta and the risk-free rate.
What is the difference between WACC and the cost of equity?
The cost of equity is the return shareholders alone require. WACC blends the cost of equity with the after-tax cost of debt, weighted by how much of each the company uses. A DCF, which values the whole firm, discounts at WACC; a Dividend Discount Model, which values only the equity claim, discounts at the cost of equity.
What is a typical WACC?
There is no single right number — it depends on the company's capital structure, its beta, and the risk-free rate in its market. Regulated utilities often sit around 4–6%, mature industrials around 8–10%, and technology or early-stage companies 9–12% or higher. See the sector table above.
Why does a small change in WACC move a DCF valuation so much?
WACC is applied as (1 + WACC) raised to the power of each forecast year, so its effect compounds — and it also sits in the denominator of the terminal value, which is usually the majority of a DCF's total value. A move from 8% to 9% can cut an intrinsic value estimate by 10–20%.