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Cost of Capital Calculator

Calculate Weighted Average Cost of Capital (WACC), equity and debt weights, and after-tax cost of debt for financial modeling.

Cost of Capital Inputs

$
$
%
%
%

Weighted Average Cost of Capital (WACC)

7.44%

Equity: 60.0% weight @ 9.50% + Debt: 40.0% weight @ 4.35% (after-tax)

After-Tax Cost of DebtTax Shield
4.35%

Pre-tax 5.50% reduced by 1.16% shield

Equity Contribution to WACC

5.70%

60.0% weight × 9.50% cost of equity

Debt Contribution to WACC

1.74%

40.0% weight × 4.35% after-tax debt

Annual Dollar Cost of Capital

$7,438,000.00

Annual required return on $100,000,000.00 total capital

Annual Interest Tax Shield

$462,000.00

Annual tax deduction savings from $40,000,000.00 debt at 21% tax

Debt-to-Equity (D/E) Ratio

0.67x

Capital mix: 60% Equity / 40% Debt

Enterprise Capital Structure Split

Total Capital$100,000,000.00
  • Shareholders' Equity$60,000,000.0060.0%
  • Corporate Debt$40,000,000.0040.0%

Capital Structure Leverage Sensitivity Analysis

Comparison of Weighted Average Cost of Capital (WACC) across varying debt-to-equity leverage mixes.

Capital Mix (Debt / Equity)Equity WeightDebt WeightBlended WACCAnnual Capital Cost
0% Debt / 100% Equity
100%0%9.50%$9,500,000.00
10% Debt / 90% Equity
90%10%8.98%$8,984,500.00
20% Debt / 80% Equity
80%20%8.47%$8,469,000.00
30% Debt / 70% Equity
70%30%7.95%$7,953,500.00
40% Debt / 60% EquityCurrent Mix
60%40%7.44%$7,438,000.00
50% Debt / 50% Equity
50%50%6.92%$6,922,500.00
60% Debt / 40% Equity
40%60%6.41%$6,407,000.00
70% Debt / 30% Equity
30%70%5.89%$5,891,500.00
80% Debt / 20% Equity
20%80%5.38%$5,376,000.00
90% Debt / 10% Equity
10%90%4.86%$4,860,500.00

WACC Derivation & Calculation Breakdown

Step-by-step mathematical calculation of the Weighted Average Cost of Capital.

  1. Determine Capital Structure Weights

    V=E+D=$60,000,000+$40,000,000=$100,000,000V = E + D = \$60,000,000 + \$40,000,000 = \$100,000,000

    Calculate total firm capital ($100,000,000) and the relative weights of equity and debt.

  2. Compute Component Weights

    we=EV=$60,000,000$100,000,000=60.00%,wd=DV=$40,000,000$100,000,000=40.00%w_e = \frac{E}{V} = \frac{\$60,000,000}{\$100,000,000} = 60.00\%, \quad w_d = \frac{D}{V} = \frac{\$40,000,000}{\$100,000,000} = 40.00\%

    Equity represents 60.00% and Debt represents 40.00% of total enterprise funding.

  3. Cost of Equity Rate

    re=9.50%r_e = 9.50\%

    Direct required rate of return for equity holders.

  4. Calculate After-Tax Cost of Debt

    rd×(1−t)=5.5%×(1−0.21)=4.35%r_d \times (1 - t) = 5.5\% \times (1 - 0.21) = 4.35\%

    Interest expense provides a corporate tax deduction. Pre-tax rate (5.5%) is reduced by the tax shield (21%).

  5. Compute Weighted Average Cost of Capital (WACC)

    WACC=(we×re)+(wd×rd×(1−t))=(0.6000×9.50%)+(0.4000×4.35%)=7.44%\text{WACC} = (w_e \times r_e) + (w_d \times r_d \times (1 - t)) = (0.6000 \times 9.50\%) + (0.4000 \times 4.35\%) = 7.44\%

    Multiply component costs by their respective capital weights and sum the equity and debt contributions.

  6. Annual Capital Financing Cost & Tax Shield Savings

    Annual Cost=$100,000,000×7.44%=$7,438,000,Tax Shield Savings=$462,000/yr\text{Annual Cost} = \$100,000,000 \times 7.44\% = \$7,438,000, \quad \text{Tax Shield Savings} = \$462,000/\text{yr}

    Annual blended financing burden on enterprise capital, alongside interest tax deductions saved.

Report tool

Understanding the Cost of Capital and WACC

The Weighted Average Cost of Capital (WACC) represents the blended rate of return a company must earn across all of its funding sources to satisfy shareholders, bondholders, and creditors. In corporate finance, cost of capital functions as the fundamental benchmark for evaluating new investments, determining corporate valuation discount rates, and optimizing capital structure.

Every business funds its operations through a combination of common equity and debt obligations. Because equity investors demand higher returns to compensate for taking residual risk, while lenders accept lower contracted interest rates with tax-deductible interest expenses, calculating WACC involves weighting each financing component by its market value. When analyzing company balance sheet productivity, you can evaluate operational earnings against deployed funds using our capital employed calculator, assess net value creation above your hurdle rate with the Economic Value Added calculator, or assess enterprise multiples with the business valuation calculator.

The WACC Formula and Mathematical Derivation

The formula for Weighted Average Cost of Capital calculates the sum of the weighted cost of equity and the weighted after-tax cost of debt:

WACC=(EV×re)+(DV×rd×(1−t))\text{WACC} = \left( \frac{E}{V} \times r_e \right) + \left( \frac{D}{V} \times r_d \times (1 - t) \right)

Where each mathematical variable is defined as follows:

  • E: Market value of total equity (shares outstanding multiplied by current share price).
  • D: Market value of total interest-bearing debt obligations (bank loans, bonds, notes payable).
  • V: Total enterprise capital, where V=E+DV = E + D.
  • w_e (E / V): The percentage weight of equity within the total capital structure.
  • w_d (D / V): The percentage weight of debt within the total capital structure.
  • r_e: The required cost of equity (expected return demanded by shareholders).
  • r_d: The pre-tax cost of debt (effective contractual interest rate or yield to maturity on debt).
  • t: The marginal corporate income tax rate, which provides the interest tax deduction shield.

Component Breakdown of Cost of Capital

1. Cost of Equity (r_e) via CAPM

Unlike debt, equity has no explicit contractual interest rate. Instead, the cost of equity represents the opportunity cost and risk premium demanded by common shareholders. You can calculate this required rate using CAPM or dividend growth models with our cost of equity calculator, or analyze pure systematic beta sensitivities in our dedicated CAPM calculator.

re=Rf+β×(Rm−Rf)r_e = R_f + \beta \times (R_m - R_f)

In this equation, RfR_f is the risk-free rate (typically the yield on 10-year US Treasury bonds), β\beta measures the sensitivity of the stock price relative to broad market fluctuations, and Rm−RfR_m - R_f represents the historical equity risk premium (ERP).

2. After-Tax Cost of Debt and the Corporate Tax Shield

Interest payments on commercial debt are tax-deductible expenses under most corporate tax codes. This tax deductibility creates an interest tax shield that reduces the true economic burden of borrowing. To isolate the direct impact of corporate tax deductions on effective borrowing costs, review the after-tax cost of debt calculator.

rd,after-tax=rd×(1−t)r_{d,\text{after-tax}} = r_d \times (1 - t)

For instance, if a corporation borrows at a 6.00% interest rate and pays a 21.00% corporate income tax rate, its after-tax cost of debt is only 6.00%×(1−0.21)=4.74%6.00\% \times (1 - 0.21) = 4.74\%. The government effectively subsidizes 1.26 percentage points of the financing cost through lower corporate income taxes.

Step-by-Step Worked WACC Example

Let us examine a mid-market manufacturing enterprise preparing a capital expenditure budget for a new production facility. The company financial profile includes:

  • Market Value of Equity (E): $60,000,000
  • Market Value of Debt (D): $40,000,000
  • Pre-tax Cost of Debt (r_d): 6.00%
  • Corporate Tax Rate (t): 21.00%
  • Risk-Free Rate (R_f): 4.20%
  • Equity Beta (β): 1.10
  • Expected Market Return (R_m): 9.20%

Step 1: Calculate Total Capital and Financing Weights

V=$60,000,000+$40,000,000=$100,000,000V = \$60{,}000{,}000 + \$40{,}000{,}000 = \$100{,}000{,}000
we=$60,000,000$100,000,000=60.00%,wd=$40,000,000$100,000,000=40.00%w_e = \frac{\$60{,}000{,}000}{\$100{,}000{,}000} = 60.00\%, \quad w_d = \frac{\$40{,}000{,}000}{\$100{,}000{,}000} = 40.00\%

Step 2: Determine Cost of Equity (CAPM)

re=4.20%+1.10×(9.20%−4.20%)=4.20%+5.50%=9.70%r_e = 4.20\% + 1.10 \times (9.20\% - 4.20\%) = 4.20\% + 5.50\% = 9.70\%

Step 3: Calculate After-Tax Cost of Debt

rd,after-tax=6.00%×(1−0.21)=4.74%r_{d,\text{after-tax}} = 6.00\% \times (1 - 0.21) = 4.74\%

Step 4: Compute Blended WACC

WACC=(0.60×9.70%)+(0.40×4.74%)=5.82%+1.896%=7.716%≈7.72%\text{WACC} = (0.60 \times 9.70\%) + (0.40 \times 4.74\%) = 5.82\% + 1.896\% = 7.716\% \approx 7.72\%

The blended Weighted Average Cost of Capital is 7.72%. For any capital project to create economic shareholder value, the expected internal rate of return (IRR) on that project must exceed 7.72%. When modeling operational fixed and variable expense hurdles, you can also determine your unit sales threshold using our break-even calculator.

How Cost of Capital Is Used in Practice

Financial ApplicationRole of WACCPractical Decision Rule
Capital Budgeting (NPV)Discount rate for project cash flowsAccept projects where Net Present Value is positive at the WACC discount rate.
Corporate Valuation (DCF)Discount rate for Free Cash Flow to Firm (FCFF)Determines total enterprise value by discounting un-levered cash flows.
Hurdle Rate ThresholdMinimum allowable return for new divisionsReject business units or initiatives earning less than the firm hurdle rate.
Capital Structure OptimizationTarget leverage mix minimizationIdentify the optimal debt-to-equity ratio that minimizes WACC and maximizes firm value.

Frequently asked questions

What is the difference between Cost of Capital and WACC?
Cost of capital is the overarching economic concept describing the required return demanded by capital providers. WACC (Weighted Average Cost of Capital) is the specific quantitative formula used to calculate that blended cost by weighting equity and after-tax debt in proportion to their market values.
Why must market values be used instead of book values for WACC?
Market values reflect current economic realities and the true cost of raising new funds in financial markets today. Book values reflect historical accounting costs that often severely underestimate the true value of equity and long-term assets.
Why is interest on debt multiplied by (1 - Tax Rate)?
In most tax jurisdictions, corporate interest expense is tax-deductible, reducing taxable income. This deduction creates an interest tax shield where the government effectively absorbs a portion of the interest cost, lowering the net after-tax expense of debt financing.
What happens to WACC if a company takes on more debt?
Initially, increasing debt lowers WACC because debt is cheaper than equity and offers a tax shield. However, as debt levels become excessive, the risk of financial distress and bankruptcy rises, causing lenders to demand higher interest rates and equity holders to demand higher risk premiums, which ultimately increases WACC.
How is WACC used in Discounted Cash Flow (DCF) valuation models?
In an enterprise DCF model, projected un-levered Free Cash Flows to Firm (FCFF) are discounted back to present value using WACC as the discount rate. This calculates the total Enterprise Value of the company before subtracting net debt to find equity value.
Can a private company calculate its WACC without publicly traded stock?
Yes. Private companies estimate their cost of equity by identifying publicly traded peer companies, calculating the average un-levered beta of those peers, re-levering the beta to match the private firm capital structure, and applying CAPM alongside current bank lending rates.

Resources and references

The formulas and methods in this calculator were checked against these independent sources.