WACC Calculator (Weighted Average Cost of Capital)

How to use this WACC calculator

What this calculator does

This calculator estimates weighted average cost of capital: the blended annual rate a company is expected to pay for debt and equity financing after reflecting the tax effect of interest expense. It is useful as a company-level discount-rate starting point for cash flows that have risk similar to the existing business. It does not determine whether a specific security is fairly priced, replace a full valuation, or automatically produce the right hurdle rate for a project whose risk differs materially from the company's normal operations. The core method follows the standard WACC identity described in the NYU Stern explanation of cost of capital.

When to use it

Use WACC when preparing a discounted cash flow valuation, screening a project with risk close to the firm's current asset base, comparing financing structures, or testing how changes in borrowing costs, equity return expectations, or tax assumptions affect a company-wide hurdle rate. For a high-risk new venture, distressed business, foreign-currency cash flow, or project outside the company's normal risk profile, a project-specific discount rate may be more appropriate.

How to calculate

1. The calculator opens with a complete demonstration: $2,000,000 of equity, $1,000,000 of debt, a 10.50% cost of equity, a 6.50% pre-tax cost of debt, and a 30.00% tax rate. Results and a validated example workbook are ready immediately.
2. Replace each demonstration value with market-based assumptions for the company being analyzed. Currency fields accept U.S.-style digits with optional commas and decimals; percent fields accept numbers such as 8.5 or 8.5%.
3. Read the WACC first, then review the equity and debt weights, after-tax debt cost, contribution cards, capital-mix chart, and calculation table. All outputs update live.
4. Select Download Excel to create a current-state OOXML workbook. Select Reset to clear the demonstration and all calculated content; export remains unavailable until a new complete valid set is entered.

Input guide

Market value of equity is a required nonnegative dollar amount representing the current value attributable to common owners. For a public company, market capitalization is a common starting point; for a private company, a defensible valuation estimate is needed. The demonstration uses $2,000,000. Raising equity while holding its cost above the after-tax debt cost usually raises WACC because equity receives more weight. Do not substitute the balance-sheet carrying amount without considering whether it reasonably approximates market value.

Market value of debt is a required nonnegative dollar amount for interest-bearing obligations. The demonstration uses $1,000,000. Increasing debt gives more weight to the after-tax borrowing cost, but this mechanical result does not capture higher default risk or the possibility that both debt and equity costs rise at aggressive leverage levels. Debt and equity cannot both be zero.

Cost of equity is a required annual percentage from 0% through 100%. The sample is 10.50%. It may be estimated with CAPM, a build-up method, or another supportable approach. A higher required equity return increases WACC in direct proportion to the equity weight. Do not enter a dollar amount or a decimal fraction such as 0.105 when the field expects 10.5.

Pre-tax cost of debt is a required annual percentage from 0% through 100%, shown as 6.50% in the example. Use the current yield or expected effective borrowing rate rather than an old coupon when the two differ. A higher debt cost increases WACC according to the debt weight and tax adjustment. The IRS overview of interest expense provides tax context, although actual deductibility can be limited and should be reviewed with a qualified adviser.

Corporate tax rate is a required percentage from 0% through 100%; the demonstration uses 30.00%. A higher tax rate lowers the standard after-tax debt cost because the formula multiplies debt cost by one minus the tax rate. Use the marginal rate relevant to the forecast and do not assume every company can realize the full tax shield in every period.

Output guide

Weighted average cost of capital is the primary annual percentage estimate. Lower values imply a lower blended financing hurdle, while higher values imply a greater required return or risk burden. Equity weight and Debt weight are exact shares of total market-value capital and sum to 100%. After-tax debt cost is the debt rate after the entered tax adjustment. Equity contribution and Debt contribution show how many percentage points each source adds to WACC; their sum equals WACC. Total capital is the dollar sum of equity and debt. Tax shield on debt cost is the percentage-point reduction from applying the tax rate to the pre-tax debt cost.

The Capital structure mix chart compares the two positive market-value sources in the same dollar unit. Its legend repeats each amount and weight. The Calculation breakdown table shows the source, market value, weight, input cost, after-tax cost, and WACC contribution. A zero debt amount is valid and produces a 100% equity structure with no debt segment; a zero equity amount is also valid. When only one source is positive, the chart is replaced by a compact single-source summary rather than a misleading one-part ring.

Worked example

With $2,000,000 of equity and $1,000,000 of debt, total capital is $3,000,000. Equity weight is 2,000,000 ÷ 3,000,000 = 66.67%, while debt weight is 33.33%. The 6.50% debt cost becomes 4.55% after tax because 6.50% × (1 – 30.00%) = 4.55%. Equity contributes 66.67% × 10.50% = 7.00 percentage points. Debt contributes 33.33% × 4.55% = 1.52 percentage points. Adding those contributions produces the first-open WACC of 8.52%. Results are estimates driven by the assumptions entered, not a recommendation to invest, borrow, or approve a project.