Weighted Average Cost of Capital (WACC) Calculator

WACC – Capital Cost Estimator

Weighted Average Cost of Capital Formula

Formula

\[ \text{WACC} = \left( \frac{E}{V} \times R_e \right) + \left( \frac{D}{V} \times R_d \times (1 - T) \right) \]

Where:

$E$ — market value of equity (e.g. market capitalization)
$D$ — market value of total debt
$V$ — total capital, $V = E + D$
$R_e$ — cost of equity (required return of shareholders)
$R_d$ — cost of debt (effective interest rate)
$T$ — corporate tax rate

The formula takes the share of the capital structure financed by each source, multiplies it by that source's cost, and adds the two parts together. The debt term is multiplied by $(1 - T)$ because interest payments are tax-deductible, which lowers the effective cost of borrowing.

Weighted Average Cost of Capital – Calculation Example

Example: a company has $800,000 in equity and $200,000 in debt, a 10% cost of equity, a 5% cost of debt, and pays a 30% corporate tax rate. Total capital is $V = 800{,}000 + 200{,}000 = 1{,}000{,}000$.

\[ \text{WACC} = \left( \frac{800{,}000}{1{,}000{,}000} \times 0.10 \right) + \left( \frac{200{,}000}{1{,}000{,}000} \times 0.05 \times (1 - 0.30) \right) \]

\[ \text{WACC} = 0.080 + 0.007 = 0.087 = 8.7\% \]

Result: WACC = 8.7%. The company must earn at least 8.7% on new investments to satisfy both its shareholders and its lenders.

How to Use the Calculator

Enter the Equity value (E) — the market value of the company's equity, such as its market capitalization.
Enter the Debt value (D) — the market value of all outstanding debt (loans, bonds, credit lines).
Enter the Cost of equity (Re) as a percentage — the return shareholders expect, often estimated with the CAPM.
Enter the Cost of debt (Rd) as a percentage — the effective interest rate the company pays on its borrowings.
Enter the Tax rate (T) as a percentage — the corporate income tax rate applied to the company's profits.
Read the resulting WACC in percent, along with a short interpretation of whether the value is low, average, or high.

What Is WACC and Why It Matters

The Weighted Average Cost of Capital is the blended, after-tax rate a company pays to finance its operations from all sources of capital. Because most firms are funded by a mix of equity and debt, no single interest rate describes their financing cost. WACC solves this by weighting each source's cost by its share of the total capital structure.

WACC is one of the most widely used figures in corporate finance. It serves as the discount rate in Discounted Cash Flow (DCF) valuation models, where future cash flows are divided by $(1 + \text{WACC})^n$ to estimate the present value of a business. It is also the standard hurdle rate for capital budgeting: a project should only be accepted if its expected return exceeds the WACC.

The interpretation of the result is straightforward. A WACC of 8.7% means that every dollar invested in the company must generate at least 8.7 cents of return per year, on average, to cover the demands of investors and creditors. A lower WACC generally means cheaper capital, higher valuations, and more investment opportunities clearing the hurdle; a higher WACC makes growth more expensive and reduces the present value of future earnings.

Because equity holders take more risk than lenders, the cost of equity is nearly always higher than the cost of debt — which is why some debt in the capital structure can actually lower WACC, up to a point. Excess debt, however, raises financial risk and eventually pushes both $R_e$ and $R_d$ higher. To judge whether the capital is being used well, compare WACC against profitability metrics such as Return on Capital Employed and Return on Equity.

Assumptions and Limitations

Market values, not book values. The formula assumes E and D are current market values. Book values from the balance sheet can distort the weights, especially for older companies.
Constant capital structure. WACC assumes the target debt-to-equity ratio stays the same over the valuation period. Large financing changes make the result less reliable.
Cost of equity is an estimate. $R_e$ is not observed directly. It is usually derived from the CAPM (risk-free rate plus beta times the market risk premium), and small changes in inputs shift WACC noticeably.
Tax shield only applies to profitable firms. The $(1 - T)$ adjustment assumes the company actually pays taxes and can deduct interest. A loss-making firm gets no immediate benefit from the tax shield.
Rounding of rates. Enter Re, Rd, and T in percent (e.g. 10 for 10%, not 0.10) — the calculator handles the conversion internally.

When evaluating a specific investment, also check that the project's risk matches the company's overall risk: WACC is only a valid hurdle rate for projects similar to the existing business. For related analysis, see the Solvency Ratio to assess debt sustainability, and the Break Even calculator to find the sales level a project must reach.

Frequently Asked Questions

What is a good or normal WACC value?

For established large-cap companies, WACC typically falls between 6% and 10%. Low-risk sectors like utilities often sit at the lower end, while startups and volatile industries can exceed 15%. Rather than chasing a universal number, compare WACC with the company's return on capital: a healthy business consistently earns more than its WACC. General benchmark bands are a rough guide only — the right rate depends on industry risk and interest rate conditions.

How do I calculate WACC by hand without a calculator?

First compute total capital $V = E + D$. Then multiply the equity share $E/V$ by the cost of equity, and the debt share $D/V$ by the after-tax cost of debt $R_d \times (1 - T)$. Add the two results. For example, with 60% equity at 12% and 40% debt at 6% and a 25% tax rate: $0.6 \times 0.12 + 0.4 \times 0.06 \times 0.75 = 0.0899$, or about 9%.

How do I estimate the cost of equity (Re) if I don't know it?

The most common method is the Capital Asset Pricing Model: $R_e = R_f + \beta \times (R_m - R_f)$, where $R_f$ is the risk-free rate (often the 10-year government bond yield), $\beta$ measures the stock's volatility versus the market, and $R_m - R_f$ is the equity risk premium, typically 4–6%. For example, a 4% risk-free rate, beta of 1.2, and 5% premium give $R_e = 10\%$. Small private firms may warrant an additional size premium.

Should I use market value or book value for equity and debt?

Use market values whenever possible. For equity, that means market capitalization (share price times shares outstanding), not the balance-sheet figure. Book equity can drastically understate a profitable company's true value and skew the weights. Debt is harder — for private firms, using book value of debt as a proxy is a common practical compromise, since the market value of bank loans is rarely observable. Just apply the choice consistently.

Why does the tax rate reduce the cost of debt but not the cost of equity?

Interest payments on debt are tax-deductible business expenses in most jurisdictions, so every dollar of interest effectively costs $1 - T$ dollars after tax — this is the interest tax shield. Dividends and capital gains paid to shareholders are not deductible, so the cost of equity gets no tax adjustment. That asymmetry is one reason debt financing is cheaper than equity financing, at least in moderate amounts.

Can WACC be negative, and what does it mean?

A negative WACC is theoretically possible but practically a red flag — it would require negative costs of capital or unusual inputs, and usually signals a data error. More common pitfalls: entering 0.10 instead of 10 for a 10% rate, using book instead of market equity, or applying a personal rather than corporate tax rate. If your result looks odd, recheck the units of Re, Rd, and T first — they should be entered in percent.

How does WACC differ from the discount rate or IRR?

WACC is often used as the discount rate in DCF valuation, but the terms aren't identical. WACC is the blended cost of financing the whole company, while a proper discount rate should reflect the risk of the specific cash flows being valued. IRR is different altogether: it's the return a project generates, not its cost. The decision rule is simple — accept a project when its IRR exceeds the WACC, assuming comparable risk.

Weighted Average Cost of Capital Calculator