The cost of capital and the discount rate are two very similar terms and can often be confused with one another. They have important distinctions that make them both necessary in deciding on whether a new investment or project will be profitable.

Cost of Capital vs. Discount Rate: An Overview

The cost of capital refers to the required return necessary to make a project or investment worthwhile. This is specifically attributed to the type of funding used to pay for the investment or project. If it is financed internally, it refers to the cost of equity. If it is financed externally, it is used to refer to the cost of debt.

The discount rate is the interest rate used to determine the present value of future cash flows in a discounted cash flow (DCF) analysis. This helps determine if the future cash flows from a project or investment will be worth more than the capital outlay needed to fund the project or investment in the present. The cost of capital is the minimum rate needed to justify the cost of a new venture, where the discount rate is the number that needs to meet or exceed the cost of capital.

Many companies calculate their weighted average cost of capital (WACC) and use it as their discount rate when budgeting for a new project.

Key Takeaways

  • The cost of capital refers to the required return needed on a project or investment to make it worthwhile.
  • The discount rate is the interest rate used to calculate the present value of future cash flows from a project or investment.
  • Many companies calculate their WACC and use it as their discount rate when budgeting for a new project.

Cost of Capital

The cost of capital is the company's required return. The company's lenders and owners don't extend financing for free; they want to be paid for delaying their own consumption and assuming investment risk. The cost of capital helps establish a benchmark return that the company must achieve to satisfy its debt and equity investors.

The most widely used method of calculating capital costs is the relative weight of all capital investment sources and then adjusting the required return accordingly.

If a firm were financed entirely by bonds or other loans, its cost of capital would be equal to its cost of debt. Conversely, if the firm were financed entirely through common or preferred stock issues, then the cost of capital would be equal to its cost of equity. Since most firms combine debt and equity financing, the WACC helps turn the cost of debt and cost of equity into one meaningful figure.

Discount Rate

It only makes sense for a company to proceed with a new project if its expected revenues are larger than its expected costs—in other words, it needs to be profitable. The discount rate makes it possible to estimate how much the project's future cash flows would be worth in the present.

An appropriate discount rate can only be determined after the firm has approximated the project's free cash flow. Once the firm has arrived at a free cash flow figure, this can be discounted to determine the net present value (NPV).

Setting the discount rate isn't always straightforward. Even though many companies use WACC as a proxy for the discount rate, other methods are used as well. In situations where the new project is considerably more or less risky than the company's normal operation, it may be best to add in a risk premium in case the cost of capital is undervalued or the project does not generate as much cash flow as expected.

Adding a risk premium to the cost of capital and using the sum as the discount rate takes into consideration the risk of investing. For this reason, the discount rate is usually always higher than the cost of capital.

The Bottom Line

The cost of capital and the discount rate work hand in hand to determine whether a prospective investment or project will be profitable. The cost of capital refers to the minimum rate of return needed from an investment to make it worthwhile, whereas the discount rate is the rate used to discount the future cash flows from an investment to the present value to determine if an investment will be profitable. The discount rate usually takes into consideration a risk premium and therefore is usually higher than the cost of capital.