What Is Weighted Average Cost of Capital (WACC)?

WACC = (E/V × Re) + (D/V × Rd × (1 − Tax Rate)), where E = market value of equity, D = market value of debt, V = E + D, Re = cost of equity, Rd = cost of debt. Cost of equity is typically estimated using the Capital Asset Pricing Model (CAPM): Re = Risk-Free Rate + Beta × Market Risk Premium. Debt is cheaper than equity (and tax-deductible), so companies with more debt tend to have lower WACCs — up to a point where financial distress risk increases the cost of both. WACC is the hurdle rate in project evaluation: projects returning more than WACC create value; projects returning less destroy it. In DCF analysis, a 1% change in WACC can change enterprise value by 10–20% — making WACC estimation one of the most consequential and debated inputs in financial modeling.

WACC is the foundation of business valuation and capital allocation. If you are raising capital, evaluating acquisitions, or building a financial model for investors, understanding your cost of capital is essential. A financial advisor or fractional CFO can build a defensible WACC calculation, model capital structure scenarios, and help you understand how financing decisions affect your cost of capital.