Real Return Calculator: Inflation-Adjusted Investment Return
When you earn a return on an investment, the number that truly matters is not the nominal return shown on your statement but the real return, which is the purchasing power you actually gained after accounting for inflation. A 7% return when inflation is 6% leaves you with only about 0.9% of real gain. This calculator applies the Fisher equation to convert a nominal return and an inflation rate into an exact real return, and compares it to the simpler approximation (nominal minus inflation) so you can see where the approximation falls short. It then projects a starting investment amount forward over a chosen number of years at both the nominal and real rates, showing the difference in account balance versus purchasing power. Enter your expected nominal return percentage, the inflation rate you want to plan for, the number of years, and your starting amount. The real value output shows what your projected balance would be worth in today's purchasing power, making it directly comparable to your current savings and spending.
Formulas
Exact real rate (Fisher equation):
real_rate = ((1 + nominal / 100) / (1 + inflation / 100)) - 1
Approximate real rate:
approx_real = nominal% - inflation%
Nominal value after N years:
nominal_value = start × (1 + nominal / 100)^years
Real value after N years (in today's purchasing power):
real_value = start × (1 + real_rate)^years
How to use this calculator
- Enter your expected nominal return percentage. For a broad US equity index fund, long-run historical nominal returns have been roughly 10% per year, though future returns will differ.
- Enter the inflation rate you want to plan for. The Federal Reserve targets 2% (PCE); the long-run CPI-U average is closer to 3%.
- Enter your starting investment amount in dollars.
- Enter the number of years for the projection.
- The calculator shows the exact real return (Fisher equation), the simpler approximation, and projects both nominal balance and real purchasing power over your chosen horizon.
Frequently asked questions
What is the Fisher equation?
The Fisher equation, developed by economist Irving Fisher, states that the real interest rate equals the nominal interest rate divided by the inflation rate (in ratio form): (1 + real) = (1 + nominal) / (1 + inflation). The approximate form (real = nominal - inflation) is widely used but understates the real rate by an amount equal to the product of the two rates, which matters more at higher rate levels.
Why does the real return matter more than the nominal return?
Nominal returns tell you how much your account balance grew. Real returns tell you how much your purchasing power grew. If your investment returned 8% but inflation was 7%, your real return is only about 0.9%, meaning you barely kept pace with rising prices. Planning with real returns gives a more accurate picture of your future standard of living.
What inflation rate should I use?
The Federal Reserve targets 2% annual inflation as measured by the Personal Consumption Expenditures (PCE) price index. The Consumer Price Index (CPI-U) has averaged around 3% over longer historical periods. For long-term planning, many financial planners use 2.5% to 3% as a baseline, but the actual rate will vary. The Bureau of Labor Statistics publishes current CPI data.
What is the real return on US equities historically?
Over the long run (roughly 1900 to 2023), US equities have returned approximately 6.5% to 7% per year in real terms, based on data from sources such as the Federal Reserve and academic research by Dimson, Marsh, and Staunton. Past performance does not guarantee future results.
Does inflation affect bonds and stocks the same way?
No. Bonds have fixed coupon payments, so inflation directly erodes their real return. An unexpected increase in inflation is particularly damaging to bondholders. Stocks have some inflation protection because companies can raise prices, though this varies by sector and time horizon. Treasury Inflation-Protected Securities (TIPS) are designed to maintain purchasing power by adjusting principal for inflation.
Official sources
- Federal Reserve: What is inflation?: federalreserve.gov/faqs/economy_14419.htm
- Bureau of Labor Statistics: Consumer Price Index: bls.gov/cpi/
- TreasuryDirect: Treasury Inflation-Protected Securities (TIPS): treasurydirect.gov/marketable-securities/tips/
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.