Weighted Average Cost of Capital Calculator
Use this tool to estimate your company's WACC based on market-value capital structure, required returns, and tax rate.
What is WACC?
WACC stands for Weighted Average Cost of Capital. It is the blended cost a company pays for the capital it uses to operate and grow. That capital typically comes from equity investors, lenders, and sometimes preferred shareholders.
In plain language, WACC is the minimum return a business should earn on new investments to satisfy its providers of capital. If a project returns less than WACC, it usually destroys value. If it returns more, it can create value.
Why WACC matters in finance
WACC is one of the most important numbers in corporate finance, valuation, and investing. It directly affects:
- Discounted Cash Flow (DCF) valuation: future cash flows are discounted by WACC to estimate present value.
- Capital budgeting: WACC acts as a hurdle rate when deciding whether to approve projects.
- Performance measurement: returns above WACC generally indicate value creation.
- M&A analysis: acquirers use WACC assumptions to evaluate purchase prices and synergies.
Breaking down the WACC formula
Core equation
WACC = (E/V × Re) + (D/V × Rd × (1 − T)) + (P/V × Rp)
- E = market value of equity
- D = market value of debt
- P = market value of preferred stock
- V = total capital = E + D + P
- Re = cost of equity
- Rd = pre-tax cost of debt
- Rp = cost of preferred stock
- T = corporate tax rate
Debt is adjusted by (1 − T) because interest expense is usually tax-deductible. That tax shield lowers the effective after-tax cost of debt.
How to use this WACC calculator
Step-by-step inputs
- Enter the market value of equity and its required return (cost of equity).
- Enter the market value of debt and pre-tax borrowing cost.
- Add preferred stock values only if your company uses this financing source.
- Enter the corporate tax rate as a percentage.
- Click Calculate WACC to see the total and each weighted component.
The calculator also provides a breakdown so you can see exactly how equity, debt, and preferred stock contribute to the final result.
Worked WACC example
Assume a company has:
- Equity value: $6,000,000 at 11% cost of equity
- Debt value: $3,000,000 at 6% pre-tax cost of debt
- Preferred value: $1,000,000 at 8% cost of preferred
- Tax rate: 25%
Total capital V = 10,000,000. So weights are 60% equity, 30% debt, and 10% preferred. Debt after tax is 6% × (1 − 25%) = 4.5%.
WACC = (0.60 × 11%) + (0.30 × 4.5%) + (0.10 × 8%) = 8.75%.
That means this company should generally target projects that return more than 8.75% to create shareholder value.
Common mistakes when calculating WACC
- Using book values instead of market values: WACC should be weighted by current market values.
- Mixing nominal and real rates: keep inflation assumptions consistent across all inputs.
- Using post-tax debt cost incorrectly: if you already use post-tax debt cost, do not tax-adjust again.
- Applying one WACC to all projects: riskier projects may require higher discount rates.
- Ignoring changing capital structure: WACC may shift over time as leverage or rates change.
How companies reduce their WACC
Improve operating risk profile
More stable cash flows can reduce perceived business risk, which often lowers both equity and debt costs.
Optimize debt levels
Moderate leverage can reduce WACC through tax shields, but too much debt increases financial risk and borrowing costs.
Strengthen credit quality
Better credit ratings and lender confidence can materially reduce borrowing spreads.
Communicate with investors
Clear strategy, transparency, and consistent performance can reduce equity risk premium assumptions.
Final takeaway
WACC is a practical decision tool, not just an academic formula. When used correctly, it helps businesses allocate capital wisely, evaluate opportunities rigorously, and make better long-term financial decisions. Use this calculator regularly whenever your financing mix or market conditions change.