Real Return and Inflation Calculator
Compare annual nominal return with inflation using the exact Fisher relation, then project future value and starting year purchasing power.
Purchasing power projection
| Year | Nominal value | Real value | Value gap |
|---|---|---|---|
| 1 | $1,080.00 | $1,048.54 | $31.46 |
Thirty year inflation scenarios
| Annual inflation | Exact real return | Real future value | Nominal and real value gap |
|---|---|---|---|
| +2.0% | +5.88% | $5,555.30 | $4,507.36 |
| +3.0% | +4.85% | $4,145.68 | $5,916.98 |
| +5.0% | +2.86% | $2,328.27 | $7,734.39 |
| +8.0% | 0.00% | $1,000.00 | $9,062.66 |
Earlier editorial review
- Reviewed
- 2026-09-25
- Methodology
- 1.1
Sources
How the calculation works
Enter an annual nominal return and an annual inflation assumption for the same period. The exact real return compares their growth factors, so a positive investment return can still leave purchasing power lower when inflation is higher.
The projection applies the same nominal return and inflation rate each year to a starting balance. It shows the future nominal balance beside its value in starting year purchasing power, with no deposits or withdrawals.
Inflation drag is the difference in percentage points between nominal return and exact real return. The nominal and real balances use different units, so their displayed gap is a comparison rather than a fee or cash charge.
The comparison table holds nominal return and the 30 year horizon fixed while changing the inflation assumption. Preset rates are editable scenarios, not current or historical inflation data.
Step by step
- Enter annual nominal return and inflation for the same period.
- Enter a starting balance and a projection horizon from zero to one hundred years.
- Compare exact and approximate real return, the percentage point gap, and projected balances.
Worked example
With a nominal annual return of 8% and annual inflation of 3%, the exact real return is ((1.08 / 1.03) − 1) × 100, or about 4.8544%. The approximate result is 8% − 3% = 5%, and inflation drag is about 3.1456 percentage points.
A starting balance of USD 1,000 grows to USD 1,080 in nominal terms after one year. Its value in starting year purchasing power is about USD 1,048.54, so the displayed gap is about USD 31.46. These are modeled values, not a forecast.
When to use this calculator
Use it to compare an annual nominal return with an inflation assumption or to illustrate how constant rates change purchasing power over time.
For a household estimate, use an inflation assumption relevant to its spending and compare alternate rates. The preset values are scenario inputs and do not represent a published inflation series.
Common input mistakes
Use annual rates that describe the same period. A monthly return and annual inflation rate need conversion before comparison.
Read inflation drag as a percentage point difference. Do not describe the gap between nominal future value and real future value as a fee or an amount removed from the balance.
Formula and units
Exact real return (%) = ((1 + nominal return / 100) / (1 + inflation / 100) − 1) × 100
Approximate real return (%) = nominal return (%) − inflation (%)
Inflation drag (percentage points) = nominal return (%) − exact real return (%)
Nominal future value = starting balance × (1 + nominal return / 100)^years
Real future value = starting balance × ((1 + nominal return / 100) / (1 + inflation / 100))^years
Nominal and real value gap = nominal future value − real future value
Both rates must be greater than negative one hundred percent. Projection rates are held constant and compounded annually. Real future value is expressed in starting year purchasing power. A negative value gap can occur with deflation.
Assumptions and limits
The projection repeats constant annual rates with annual compounding for up to one hundred years. It excludes contributions, withdrawals, fees, taxes, volatility, and sequence risk. The inflation input is an assumption, not a retrieved index or forecast. Personal spending inflation can differ from a broad price index. Currency formatting only labels the entered amount; it does not convert currencies.
Key terms
- Nominal return
- Investment growth rate before adjusting for changes in prices.
- Exact real return
- Growth rate after dividing the nominal growth factor by the inflation growth factor.
- Inflation drag
- The percentage point difference between nominal return and exact real return.
Related analysis
Use Time to FIRE to test an inflation adjusted spending target, or Total Return Calculator to examine nominal investment return. Sequence of Returns shows how changing yearly returns differ from this constant rate illustration.
This calculator compares purchasing power under stated rates. A spending plan may need a personal inflation assumption that differs from a broad price index.
FAQ
What is the difference between exact and approximate real return?
The approximate method subtracts inflation from nominal return. The exact Fisher relation divides the nominal growth factor by the inflation growth factor, then subtracts one. At 8% nominal return and 3% inflation, the exact result is about 4.8544%, while the subtraction gives 5%.
What does inflation drag mean here?
It is the percentage point difference between nominal return and exact real return. At 8% nominal return and 3% inflation, the drag is about 3.1456 percentage points. It is not an account fee or the percentage of investment gains consumed.
Can the real return be negative when the nominal return is positive?
Yes. When inflation exceeds the nominal return, the exact real return is negative, which means the modeled balance buys less than before. The result depends on the two entered annual rates.
Does the nominal and real value gap represent money lost?
No. Nominal future value is stated in future currency, while real future value is stated in starting year purchasing power. The difference explains the inflation adjustment and is not a fee, withdrawal, or cash loss.
Can I compare rates measured over different periods?
Convert them to the same interval before using the calculator. For example, compare annual nominal return with annual inflation, not a monthly return with an annual inflation rate.
Related tools
Time to FIRE can test an inflation adjusted target. Total Return Calculator examines nominal return. Sequence of Returns illustrates changing annual returns, which this constant rate projection omits.