How to Calculate WACC: Formula, Steps, and Worked Example
Calculate WACC from equity and debt weights, required returns, and the tax shield—then check the result with a worked example.
How to Calculate WACC: Formula, Steps, and Worked Example
Updated July 2026 · ~10 min read
WACC combines the required returns of financing sources using weights intended to represent the relevant capital structure. It is not directly observable and is not a company-wide constant. Market values, target leverage, debt yields, beta estimates, tax deductibility, preferred stock, leases, currency, and project risk can materially change the result.
When WACC hygiene unlocks models
- DCF practice: you discount free cash flows to the firm at financing-weighted hurdle rates.
- Capital structure class: students reconcile book leverage with market leverage.
- Risk oversight: boards stress-test hurdle rates when beta benchmarks shift.
- Not guaranteed forecasts: future leverage paths differ from snapshots.
The formula
WACC = (E/V)×Re + (D/V)×Rd×(1−Tc) E/V and D/V use market-value weights; Re often from CAPM; Rd from bond yields Tc = marginal corporate tax rate applied to interest deductibility
The debt tax shield applies only when interest is deductible and usable. Statutory tax rates, cash taxes, marginal rates, and effective rates are not interchangeable.
A transparent WACC scenario
With 60% equity at 9%, 40% debt at 5%, and an assumed usable 25% marginal tax rate, WACC is 6.9%. This is a scenario output, not an exact hurdle rate for every project or future period.
Choose consistent capital claims
- Use current or target market-value weights on a consistent date.
- Define whether debt is gross or net of excess cash.
- Model preferred stock, leases, minority interests, or other claims when material.
- Match the discount rate to the cash-flow currency and risk.
Stress the estimate
Vary beta, market risk premium, debt spread, tax usability, and target leverage rather than presenting one decimal-heavy WACC as certain.
Common mistakes
- Mixing book weights with market-based required returns.
- Using a statutory tax rate without checking deductibility or taxable income.
- Using current debt coupon instead of a relevant current borrowing cost.
- Applying one corporate WACC to projects with different risk or currency.
- Ignoring preferred stock, leases, excess cash, or changing leverage.
Try the calculator
Use the interactive calculator to plug in your numbers and see results instantly—without redoing the math by hand.
Open WACC calculator →FAQ
Should WACC use market or book weights?
Market or target market-value weights are commonly used for forward-looking finance analysis, but the appropriate definition depends on the decision and available data.
Which tax rate belongs in WACC?
A marginal rate that reflects usable interest deductibility under the modeled scenario, not automatically the statutory or historical effective rate.
Is WACC the same for every project?
No. Project risk, currency, duration, leverage, and geography can require adjustments or a different rate.
How precise is WACC?
It is an estimate. Scenario ranges are usually more informative than a single precise number.
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Open the Risk & Portfolio hub →Educational Disclaimer
This article is for educational and informational purposes only and should not be considered investment, financial, tax, or legal advice. Market information may change over time, and readers should verify important details independently before making financial decisions.