What is WACC and why does it matter?

WACC (Weighted Average Cost of Capital) is the blended required return a company must earn on its assets to satisfy all providers of capital — equity holders, bondholders and preferred shareholders. It is the standard discount rate used in DCF valuations and as the hurdle rate for capital-budgeting decisions. A project must generate a return above the WACC to create value.

What is the WACC formula?

WACC = (E/V) times Re + (D/V) times Rd times (1 minus Tc), where E is market value of equity, D is market value of debt, V = E + D, Re is the cost of equity, Rd is the pre-tax cost of debt and Tc is the corporate tax rate. If preferred equity P is present, add (P/V) times Rp and set V = E + D + P.

How is the cost of equity calculated with CAPM?

The Capital Asset Pricing Model gives Re = Rf + beta times (Rm minus Rf). Rf is the risk-free rate (typically a government bond yield matching the project horizon), beta measures the stock's sensitivity to market movements, and (Rm minus Rf) is the equity risk premium — the extra return investors demand for bearing market risk, historically around 4–6% in developed markets.

Why does debt get a tax shield but equity does not?

Interest payments on debt are tax-deductible in most jurisdictions. A company paying 6% on debt with a 25% tax rate effectively pays only 4.5% after the tax saving. Dividends on equity are paid from after-tax profits, so there is no equivalent deduction. This asymmetry makes debt cheaper on an after-tax basis and is why companies use some leverage to lower their WACC.

Should I use book value or market value for the weights?

Market values. Book (balance-sheet) values reflect historical costs and accounting choices, not the current opportunity cost of capital. The equity weight should be the current market capitalisation; the debt weight should be the current market value of outstanding debt (often close to face value for investment-grade bonds). Using book weights can materially distort the WACC.

What is a typical WACC for a large company?

It varies by industry, leverage and macro environment. In 2024, large-cap US companies typically had WACCs in the 8–12% range; capital-light tech firms often sat above 10% due to higher equity betas, while utilities or infrastructure businesses with stable cash flows and higher debt capacities often fell in the 5–7% range. The risk-free rate anchors everything, so WACCs shift as interest rates move.

WACC Calculator — Gera Tools

The Weighted Average Cost of Capital (WACC) is the single most important discount rate in corporate finance. It tells you what return a business must earn across all its assets simply to break even in the eyes of its investors. Every DCF model, every capital-budgeting decision and every M&A fairness opinion starts here.

This calculator implements the full two-layer WACC formula with an optional CAPM module for deriving the cost of equity, a tax-shield adjustment on debt, and support for preferred equity as a third capital tier. Everything runs in your browser — no data leaves your device.

How it works

The core formula blends each source of capital by its weight in the total capital structure:

WACC = (E/V) x Re + (D/V) x Rd x (1 - Tc)

E — market value of equity (market capitalisation)
D — market value of debt (bonds + bank loans at current market prices)
V = E + D — total capital
Re — cost of equity
Rd — pre-tax cost of debt (bond yield / coupon rate)
Tc — corporate tax rate

If preferred equity P is present, the formula extends to:

WACC = (E/V) x Re + (P/V) x Rp + (D/V) x Rd x (1 - Tc)

where V = E + D + P and Rp is the preferred dividend yield. Preferred dividends carry no tax deduction, so Rp enters without a tax adjustment.

CAPM: where Re comes from

Rather than guessing the cost of equity, the Capital Asset Pricing Model derives it from first principles:

Re = Rf + beta x (Rm - Rf)

Rf — risk-free rate (e.g. the current 10-year gilt or Treasury yield)
beta — the stock’s systematic risk relative to the market (beta = 1 means the stock moves with the index; beta = 1.5 means 50% more volatile)
(Rm - Rf) — equity risk premium, the extra return demanded for bearing market risk

The tool computes the equity risk premium internally and shows it in the detail panel, so you can verify the CAPM arithmetic step by step.

The debt tax shield

Debt is uniquely advantaged: interest payments are tax-deductible in most jurisdictions. A company paying a 6% coupon with a 25% tax rate only bears a net cost of 4.5% because the government effectively subsidises 1.5 percentage points. The formula captures this as Rd x (1 - Tc).

Worked example

A mid-cap technology firm has the following capital structure and rates:

Item	Value
Market value of equity	$800 m
Market value of debt	$200 m
Risk-free rate (Rf)	4.5%
Equity beta	1.10
Expected market return (Rm)	10.0%
Pre-tax cost of debt (Rd)	6.0%
Corporate tax rate (Tc)	25%

Step 1 — Capital weights:

V = $800m + $200m = $1,000m
Equity weight: 800/1000 = 80%
Debt weight: 200/1000 = 20%

Step 2 — Cost of equity via CAPM:

ERP = 10.0% - 4.5% = 5.5%
Re = 4.5% + 1.10 x 5.5% = 4.5% + 6.05% = 10.55%

Step 3 — After-tax cost of debt:

RdAfterTax = 6.0% x (1 - 0.25) = 4.50%

Step 4 — WACC:

WACC = 0.80 x 10.55% + 0.20 x 4.50%
WACC = 8.44% + 0.90% = 9.34%

This firm should accept any project returning more than 9.34%; below that, the investment destroys shareholder value. Enter the same numbers in the calculator above to verify.