Real Rate of Return Calculator
Calculate the inflation-adjusted real rate of return on an investment from its nominal return and the inflation rate, using the Fisher equation.
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Real Rate of Return (Fisher Equation)
4.85%
Simple Approximation
5.00%
How Real Rate of Return Is Calculated
Your nominal (stated) investment return doesn't tell the whole story — inflation erodes the purchasing power of those gains. The real rate of return strips inflation out, showing how much your money actually grew in terms of what it can buy. Many people approximate it by simply subtracting inflation from the nominal return, but the more accurate method is the Fisher equation, which properly accounts for the compounding interaction between the two rates. This calculator uses the Fisher equation for its main result and shows the simple approximation alongside it for comparison.
Simple Approximation: Real Rate ≈ Nominal − Inflation
Example
An investment with an 8% nominal return during a year of 3% inflation has a Fisher real rate of return of (1.08 ÷ 1.03) − 1 = 4.85%. The simple approximation gives 8% − 3% = 5%, which is close but slightly overstates the real return — the gap grows wider as the rates involved get larger.
Common Use Cases
- Judging whether an investment is actually growing your wealth after inflation.
- Comparing returns across different time periods with different inflation rates.
- Setting realistic long-term retirement or savings growth assumptions.
- Evaluating whether a savings account or bond yield is keeping pace with rising prices.
FAQs
Why use the Fisher equation instead of simple subtraction?
Simple subtraction ignores the fact that inflation also eats into the return earned on top of the original investment, not just the principal. The Fisher equation divides by (1 + inflation) to capture that compounding effect, making it more accurate — especially when nominal returns or inflation are high.
Can the real rate of return be negative?
Yes — if inflation is higher than your nominal return, the real rate of return is negative, meaning your money is losing purchasing power even though its dollar value grew.
What inflation rate should I use?
Use the inflation rate for the same period as your nominal return, typically measured by a consumer price index (CPI) for that year or timeframe, so the two figures line up correctly.