Why cost of capital matters to a first-time founder
Cost of capital is a hurdle for investment decisions. A project that earns less than the return expected by funders may reduce value even if it reports an accounting profit. For founders, the figure also explains why equity is not free: investors accept risk and expect compensation for it.
Examples of cost of capital
A company is funded 40% by debt costing 6% after tax and 60% by equity expected to return 14%. Its simplified weighted cost of capital is (40% × 6%) + (60% × 14%) = 10.8%. A project expected to return 9% would fall below that benchmark, before adjusting for project-specific risk.
Common misunderstanding
Cost of capital is not the interest rate on a loan. Interest covers debt only; cost of capital can combine debt and equity. It is also an estimate, not an invoice. Tax treatment, market values, risk, and jurisdiction affect the calculation, so a headline percentage should not be treated as universal.
When to use it
Use it when assessing major investments, acquisitions, valuations, or financing choices. Very early companies rarely have enough market evidence for a precise figure, so test a sensible range instead of presenting false accuracy. Use after-tax debt costs only where local tax rules permit the relevant interest deduction.