Equity Risk Premium Calculator

Stocks are supposed to pay more than bonds, and the extra pay is the equity risk premium. It prices stocks, sets discount rates in valuations, and drives the capital asset pricing model. This equity risk premium calculator computes the premium from your expected market return and risk-free rate, then applies it through CAPM to any stock beta for a required return you can actually use.

Quick Answer

The premium, and why it moves markets

The equity risk premium is the market price for bearing stock market risk. When it is high, investors demand heavy compensation to hold equities, which usually means stock prices are low relative to earnings. When it is compressed, investors are accepting equity risk cheaply, which usually means prices are high. Valuation models like discounted cash flow live or die on this input, because a higher premium raises the discount rate and lowers present values.

That is why the premium is argued over so much. Two analysts can agree on a company’s cash flows and still reach very different values simply because they used different premiums. The calculator keeps that argument honest: it shows the subtraction, the CAPM result, and a verdict against the historical band, so a wild input cannot hide inside a polished valuation.

The bars above split the worked example required return into its two parts. The risk-free rate is the return for waiting, and the stock premium is the return for bearing risk. If either part moves, the required return moves with it.

Historical or forward-looking: which number should you trust?

Neither method is right on its own, and the honest approach is to check one against the other. The historical method averages decades of stock returns minus bond returns. The forward-looking, or implied, method backs a premium out of current prices, dividends, buybacks, and growth expectations. If your forward-looking premium sits far from the historical band, one of your inputs is probably off.

This calculator takes the forward-looking route: you supply the expected market return, and it derives the premium. Use the historical band as a sanity check, not as a substitute for thinking. Research on equity risk premiums by NYU Stern professor Aswath Damodaran, and the historical datasets he publishes, are the standard starting point for that comparison, and they are listed in the references below.

From premium to required return: the CAPM step

The market-wide premium prices equities as a group. For one stock, CAPM scales it by beta: required return equals the risk-free rate plus beta times ERP. A beta of 1.2 on the worked example inputs gives 4.25% plus 1.2 times 4.75%, which is 9.95%. The stock specific premium, the part above the risk-free rate, is 5.70%. Beta above 1.0 demands a larger premium, beta below 1.0 a smaller one, and beta exactly 1.0 gives the market premium itself.

That required return is the discount rate side of valuation: it feeds directly into cost of equity and weighted average cost of capital work. For the cost of raising more equity, see our cost of new equity calculator. To check the beta you are using, see our beta calculator. For the market return assumption itself, the long-run picture is in our S&P 500 returns calculator, and a single stock valuation multiple is covered by our price earnings ratio calculator.

All four rows use the worked example inputs of 9% market return and 4.25% risk-free rate, so only beta changes. Enter any of these betas in the calculator and the tool reproduces the row exactly.

How to use this calculator without fooling yourself

Start with a market return you can defend, not one that gives the answer you want. A market return picked from a single strong year will inflate the premium, and a risk-free rate picked from the wrong horizon will distort it in the other direction. Check that the risk-free rate matches the currency and horizon of the cash flows you are valuing: a US Treasury yield belongs with US dollar cash flows, not with euro cash flows.

Then read the verdict before you use the number. A premium below 3% says equities are priced richly against bonds, a premium in the 3% to 5.5% range sits in line with long-run history, a premium above 5.5% to 7% is elevated, and anything above 7% should prompt a recheck of both inputs. Negative inputs are clamped to zero by the tool, and an empty input is treated as zero, so a blank field will never silently produce a premium from a missing number, and for beta that zero is not the market result: it gives the risk-free rate instead.

What competing ERP calculators miss

Nearly every ERP calculator on the web does one subtraction and stops: no CAPM application, no verdict on whether the result is sane, and no discussion of historical versus forward-looking methods. Users get a number with no way to judge it. One rival even adds an unexplained adjusted premium on top of its result, with no formula shown for the adjustment, which is exactly the kind of hidden step that makes a valuation hard to audit.

The strongest rival tool solves CAPM for any missing input, which is genuinely useful, but it is framed as a CAPM tool rather than an ERP tool, and it does not debate the historical versus implied choice or benchmark the premium. This calculator keeps ERP first, applies the premium through CAPM to a real beta, benchmarks the result against the historical band, and explains the method debate plainly.

Frequently Asked Questions

Add This Calculator to Your Website

References