i What this calculator does
The weighted average cost of capital is the blended return a company must earn to satisfy everyone who funds it. It is the discount rate a discounted cash flow model needs, and the hurdle a project has to clear to create value.
Debt is cheaper than equity and interest is tax deductible, which is why the after-tax cost of debt appears. The South African corporate rate of 27% is applied to that shield.
This calculator is for educational purposes only. Results are estimates and may vary depending on market conditions, spreads, commissions, platform settings, and exchange rates. It should not be considered financial advice.
How to use the WACC Calculator
Every field has a working default, so the calculator produces a result the moment the page loads. Replace the defaults with your own figures and the output updates when you press the button.
- 1. Market Value of Equity (R million)
- 2. Market Value of Debt (R million)
- 3. Risk-Free Rate (%) Long-dated SA government bond yield
- 4. Equity Risk Premium (%)
- 5. Beta Volatility relative to the market
- 6. Cost of Debt Before Tax (%)
The result panel reports:
- WACC Use this as the discount rate
- Cost of Equity From CAPM
- After-Tax Cost of Debt After the
Alongside the headline figures, the calculator reports equity weight, debt weight, total capital, tax shield on debt. Those are the numbers that usually explain why the headline result came out where it did.
The breakdown below the result shows every step of the arithmetic, so you can check the figure rather than trust it. The formula panel names each input as it is used, which is useful if you want to reproduce the calculation in a spreadsheet.
Frequently asked questions
What risk-free rate applies in South Africa?
The yield on a long-dated South African government bond, typically the ten-year or the R2035, is the usual proxy. It is materially higher than developed-market equivalents, which is why South African discount rates are higher and valuations more sensitive to them.
What equity risk premium should I use?
Five to seven percent is the common range for South Africa. Some practitioners add a separate country risk premium; others treat the higher local bond yield as already carrying it. Adding both double counts.
Why is debt cheaper than equity?
Debt holders rank ahead of shareholders and usually hold security, so they accept a lower return. Interest is also deductible against tax, which reduces the effective cost further. That is the tax shield the formula applies.
Should I use book or market values for the weights?
Market values, because WACC is a forward-looking rate and the question is what capital costs today. Book values reflect historical transactions. For debt the two are often close; for equity they rarely are.
Does a higher debt weight always lower the WACC?
Only up to a point. Beyond a certain level, lenders demand more and the cost of equity rises because the equity is riskier, which pushes the WACC back up. The relationship is a curve rather than a line.
What if the company has no debt?
Then the WACC equals the cost of equity. That is a valid outcome, and the calculator handles it: set the market value of debt to zero.
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