Real Rate of Return Calculator

What this calculator does

Find out how much your money really grows once rising prices are taken into account. A savings account paying 5% sounds like 5% more money a year from now, and in dollars it is. But if prices rise 3% over the same year, each of those dollars buys less. So the gain in what you can actually buy is smaller. The real rate of return measures that gain in buying power: the growth left over once inflation has had its share.

This calculator uses the exact Fisher equation, not the common shortcut of subtracting inflation from the stated return. Economists call the stated return the nominal return. The calculator can also work backwards. It can find the stated return you need to hit a real target. Or it can find the inflation rate at which a given return would only break even. Add a tax rate to see an after-tax real return. Add an amount and a number of years to see the result in dollars. You'll get it both in future money and in today's buying power.

Where it's used

Why this math matters outside the classroom:

• Checking savings rates. A saver sees that 5% interest with 3% inflation is a real gain of 1.05 ÷ 1.03 − 1, about 1.94% a year.
• Retirement planning. Planners project savings with a real return, such as 4%, so that the final balance is already in today's dollars.
• Economics class. Students use the Fisher equation to show that a 10% return with 8% inflation leaves only about 1.85% of real growth.
• Salary negotiations. A worker given a 4% raise in a year of 6% inflation finds that real pay fell by about 1.9%.
• Comparing bonds. Investors compare an ordinary bond's yield with an inflation-protected one by finding the break-even inflation rate.

Grade level and standards: Grades 7–8; Common Core State Standards for Mathematics 7.RP.A.3. © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.

How to use it

1. Choose what to solve for: the real return, the stated (nominal) return you need, or the break-even inflation rate.
2. Enter the two rates the calculator asks for, all as yearly percentages.
3. If you like, enter a tax rate on the return (real-return mode only). You can also add an amount and a number of years for a dollar projection.
4. Read the exact answer and compare it with the quick estimate. Then follow the steps to see the Fisher equation at work.

What the inputs mean

Nominal return per year

The return as it's quoted, before any allowance for rising prices. That might be a savings rate, a bond yield or a fund's average yearly return. You can enter a loss as a negative number.

Inflation rate per year

How much the prices you care about rise each year. A general consumer price index (the government's measure of everyday prices) is the usual choice. You can also use an expected future rate or your own cost of living.

Real return you want per year

The growth in buying power you want each year. It's used when solving for the stated return or the break-even inflation rate.

Tax rate on the return (optional)

If tax is due on the return each year, the after-tax return is the stated return times (1 − tax rate). Tax is charged on the stated gain, not the real one. That's why inflation and tax together can push a real return below zero.

Amount invested (optional)

Optional. Add a number of years too, and you'll see what the amount grows to in future dollars. You'll also see what that's worth in today's dollars.

Formula and method

1 + nominal = (1 + real) × (1 + inflation)
real = (1 + nominal) ÷ (1 + inflation) − 1
nominal = (1 + real) × (1 + inflation) − 1
after-tax nominal = nominal × (1 − tax rate)
value in today's dollars = amount × (1 + real)^years

In these formulas, nominal is the stated yearly return and inflation is the yearly rise in prices. Real is the yearly growth in buying power, all written as decimals (7% is 0.07). Growth rates combine by multiplying, not adding. Say your money grows by a factor of 1.07 while prices grow by a factor of 1.03. Then your buying power grows by 1.07 ÷ 1.03. Subtracting 1 turns that factor back into a rate. This rule is called the Fisher equation, after the economist Irving Fisher.

The familiar shortcut, real ≈ nominal − inflation, leaves out the small product of the two rates. It's close when both rates are low. But it always overstates a positive real return a little, and the error grows when inflation is high. At 7% and 3% the shortcut says 4%, while the exact figure is about 3.88%.

For the dollar projection, the amount grows once a year at the stated rate. Growing it at the real rate instead gives that same result divided by (1 + inflation)^years. That's the future balance written in today's prices.

Worked example

An investment is expected to return 7% a year while inflation runs at 3%. You invest $10,000 for 10 years.

1. Divide the growth factors: 1.07 ÷ 1.03 = 1.03883495.
2. Subtract 1 and write it as a percent: the real return is 3.8835% a year.
3. The quick estimate, 7% − 3%, would have said 4%.
4. In future dollars: $10,000 × 1.07^10 = $19,671.51.
5. In today's dollars: $10,000 × 1.03883495^10 = $14,637.45. So inflation accounts for a gap of $5,034.06.

Result: The real rate of return is 3.8835% a year. The $10,000 grows to $19,671.51, which will buy what $14,637.45 buys today.

Understanding the result

A positive real return means your money is gaining buying power. A negative one means it's losing ground to prices, even if the balance is rising. Cash in a low-rate account while inflation is high is the classic case. The stated return is positive, but the real one is negative.

When you solve for the stated return needed, the answer is the lowest return that keeps your buying power growing at the target rate. Solving for break-even inflation shows how much inflation a fixed return can absorb. Past that point, your real gain falls below the target. Set the target to 0% to find where it falls to zero.

Compare real returns, not stated ones, when you look across decades or countries with different inflation. A 10% return when prices rise 8% is worse in real terms than a 4% return when prices rise 1%.

Assumptions and limitations

• All rates are effective yearly rates for the same period, and they stay the same over the projection.
• Tax, if entered, is charged on the whole stated return each year.
• The projection grows once a year, with no further deposits or withdrawals.
• Inflation is one average figure. Your own costs may rise faster or slower than any index.
• Real tax rules are more complex. Rates vary by account type and income, gains may be taxed later, and losses may offset other income. Treat the after-tax figure as an illustration.
• Future returns and inflation are uncertain. This is a general educational tool, not investment advice.

Frequently asked questions

How this calculator is checked

Method: The exact Fisher relation (1 + nominal) = (1 + real)(1 + inflation), rearranged for each unknown; after-tax nominal return as nominal × (1 − tax rate); yearly compounding for the projection. The calculation is covered by automated tests with known reference values and edge cases. Last updated 2026-10-18. Found a problem? Tell us.

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