TL;DR: Cost of capital is the price a company pays to fund itself, whether through debt, equity, or a blend. For debt, the cost is interest and fees. For equity, the cost is the ownership and future value given up. Comparing the two on a like-for-like basis is central to financing decisions.
Cost of capital is what it costs a company to raise and use money. Different sources carry different costs. Debt has a relatively visible cost: interest, plus any fees. Equity has a less visible but often larger cost: the share of future value handed to investors, which can far exceed the interest on a loan if the company succeeds. A company's overall cost of capital blends these across its financing sources.
The common mistake is to compare a loan's interest rate against equity as if equity were free because it has no monthly payment. It is not. Selling equity means giving up a permanent share of the company's future value, which is frequently the most expensive capital of all for a successful business. The right comparison weighs the full cost of each option, including dilution and control, not just the headline interest rate.
This is the core of the case for minimally dilutive debt: for a company confident in its trajectory, debt's defined cost can be considerably cheaper than the ownership surrendered in an equity round, in exchange for taking on a repayment obligation.
Is debt always cheaper than equity? Not always, but for a company that grows successfully, equity is frequently the more expensive option, because the value given up can far exceed the cost of a loan. The trade-off is debt's repayment obligation.
How should founders compare financing options? On total cost of capital relative to the dilution and control retained, rather than on interest rate alone.
Related terms: Equity Dilution · Minimally Dilutive Capital · Venture Debt · IRR
