How the exact (Fisher) real rate on this page is usually characterised, with your result marked. The bands are descriptive conventions, not rules — what counts as a high or low real rate depends on the economy and the horizon. The real rate is computed with the same Fisher formula as the calculator above.
Range
What it means for purchasing power
Below 0%
Negative real rate — inflation outpaces the nominal return, so money loses purchasing power despite a growing balance.
0% – 1%
Barely positive; the return roughly treads water against inflation, with little real gain.
1% – 3%
Solidly positive — a typical reward for saving when inflation is contained.
Above 3%
Strongly positive real return; attractive for savers but often a sign of tight credit conditions.
◀ your real rate (3.88%)
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What it calculates: Real Interest Rate, Approximate Real Rate.
The approximation simply subtracts: 7 − 3 = 4%. The exact Fisher equation divides instead — (1.07 / 1.03) − 1 = 3.883% — because the inflation adjustment applies to the whole grown balance, not just the principal. The 11.7 basis point gap is small here and grows with both rates.
At higher levels it stops being a rounding difference. A 40% nominal rate against 30% inflation approximates to 10% and is exactly 7.69%, a quarter of the return gone. In high-inflation economies the approximation is not usable, which is why the exact form is the one central banks and bond markets work with.
Money in a 2% account during 5% inflation loses 2.86% a year
When inflation exceeds the nominal rate, the real rate is negative and savers lose purchasing power while their balance grows. This was the condition across most developed economies for much of the 2010s and again in 2021-22, and it is not an anomaly — it is a deliberate policy outcome when central banks hold rates below inflation to support demand.
The consequence for savers is direct: a nominally positive return can be a real loss, and cash held through a period of negative real rates is being quietly taxed. It also transfers value from lenders to borrowers, since debts are repaid in money worth less than when borrowed, which is part of why inflation erodes the real burden of fixed-rate mortgages and government debt alike.
The real rate you agreed to is not the one you got
When a rate is set, the real return depends on inflation that has not happened yet. Lenders price in expected inflation; what they actually earn depends on realised inflation. A period where inflation surprises upward transfers value to borrowers, and one where it surprises downward does the reverse.
Markets provide a read on expectations through the gap between nominal government bonds and inflation-linked ones — the breakeven inflation rate. Comparing that against the realised figure afterwards is how the surprise is measured, and over 2021-22 that surprise was among the largest in forty years.
Tax, which is charged on the nominal return
Tax is applied to nominal interest, not real. A 7% return taxed at 30% leaves 4.9% nominal, which against 3% inflation is a real after-tax return of about 1.84% — less than half the pre-tax real rate. In periods of high inflation and positive nominal rates, tax on the inflation component alone can turn a positive real return negative.
The calculation also uses one inflation figure, while the relevant rate is the one applying to whatever you would otherwise buy. For someone whose spending is concentrated in a category rising faster than the index, the effective real return is lower than the headline calculation suggests.
Frequently Asked Questions
What is the Fisher effect?
The Fisher effect describes the relationship between nominal interest rates, real interest rates, and inflation. It states that the nominal rate roughly equals the real rate plus expected inflation, which is why subtracting inflation from a nominal rate gives an approximate real return.
What is the difference between ex ante and ex post real rates?
An ex ante real rate uses expected inflation and is the rate borrowers and lenders have in mind when agreeing terms. An ex post real rate uses the inflation that actually occurred, so it is only known after the fact and can diverge from expectations.
Why does the approximation drift at high inflation?
The simple subtraction ignores the cross term between the nominal rate and inflation. At low inflation that term is tiny, but as inflation climbs it becomes significant, so the approximation increasingly overstates the true real rate.
Which result should I rely on?
For precision, use the exact Fisher figure, especially when inflation is high. The approximation is fine for quick mental estimates when both rates are small and you only need a rough sense of the real return.
Does this account for taxes?
No. Interest is often taxed on a nominal basis, which lowers your after-tax real return below the figure shown here. To capture that, you would apply your tax rate to the nominal interest before deflating.
Should I use expected or actual inflation?
It depends on the question. Use expected inflation to judge a rate at the time of a decision, and actual inflation to evaluate the real return that was ultimately realised over the period.
Why is the exact rate lower than the approximation here?
Dividing by the gross inflation factor scales down the real return slightly more than a plain subtraction does, so the exact Fisher value comes in just below the nominal-minus-inflation estimate.
Sources & References
Figures on this page are checked against primary, authoritative sources. Links open in a new tab.
The nominal rate and inflation rate cover the same time horizon and compounding basis.
The inflation figure used represents the relevant expected or realised rate for the period.
Rates are entered as annual percentages unless you adjust both consistently for another frequency.
Where it stops
Using expected inflation gives an ex ante rate that can differ from the ex post outcome.
The approximation grows increasingly inaccurate as inflation rises into double digits.
It ignores taxes on nominal interest, which reduce the after-tax real return further.
Related Calculators
Fisher EquationSolve (1 + i) = (1 + r)(1 + π) for the nominal rate, the real rate or expected inflation, exactly.
Inflation RateThe inflation rate between two CPI readings, with the index change alongside the percentage.
Purchasing PowerWhat a sum will still buy after years of inflation, and how much of its value has gone.
Quantity Theory of MoneyMV = PY solved for nominal output and the price level, the identity behind most monetary inflation arguments.
Personal Inflation RateYour own inflation rate from BLS price changes weighted by how you actually spend, against the official CPI-U figure.
ShrinkflationThe real price rise when a product shrinks: price per ounce, gram or sheet before and after, the way BLS counts it.
Real WageTwo paychecks from different years compared in what they buy, on the US CPI-U, with the pay that would have kept pace and the real raise from any raise and inflation rate.
GDP DeflatorThe broadest price index there is — nominal over real GDP — with the price change since the base year.
Results are estimates for planning and analysis based on the figures you enter. They are not accounting, tax, or financial advice — verify with your own records and a qualified professional before making decisions.
Sudha, J. (2026, September 12). Real Interest Rate Calculator. Calculator Matters. https://calculatormatters.com/economics/real-interest-rate-calculator/
Published the calculator with its formula, worked example, assumptions, limitations and a bespoke guide, and added an automated formula test suite covering it.
Verified the exact Fisher relation against the subtract-and-go approximation and measured where the two diverge, so the page can state the gap rather than assert it.
Retitled around the real return after inflation, and linked the new Fisher equation calculator.
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