Inflation
Nominal return, real return, and the gap between them
How to convert a headline return into a real, post-inflation one, why the exact formula differs from simple subtraction, and where that gap matters.
The short answer: A real return is what is left after inflation, and it is the only return that tells you whether you can buy more than you could before. The approximation everyone uses — nominal minus inflation — is close enough at low rates and drifts as rates rise, because the correct relationship is multiplicative rather than additive. The consequence that matters is that a positive nominal return can be a negative real one: a savings account paying 3% while prices rise 6% loses about 2.8% of purchasing power a year, and does so invisibly, because the balance on the statement is going up the whole time.
Key points
- Real return = (1 + nominal) ÷ (1 + inflation) − 1; subtraction is an approximation that drifts as rates rise.
- A positive nominal return can be a negative real one, which is why a growing balance is not evidence of progress.
- Compute the real return after tax, not before — tax is applied to the nominal gain, including the inflation part.
- Over long horizons small real differences dominate, because they compound while the nominal illusion does not.
Real return from nominal: Real = (1 + nominal) ÷ (1 + inflation) − 1
- nominal — the return actually earned, as a decimal.
- inflation — the rate at which the prices you face rose, as a decimal.
- The familiar "nominal − inflation" is the first-order approximation of this, and it overstates the real return.
Where the approximation drifts
- 7% nominal, 3% inflation — approximate
- 4.00%
- 7% nominal, 3% inflation — exact
- 1.07 ÷ 1.03 − 1 = 3.88%
- 12% nominal, 8% inflation — approximate
- 4.00%
- 12% nominal, 8% inflation — exact
- 1.12 ÷ 1.08 − 1 = 3.70%
- 4% nominal, 6% inflation — exact
- 1.04 ÷ 1.06 − 1 = −1.89%
The approximation is fine for a mental check and understates the damage at higher rates. The last row is the important one: a positive nominal return that is losing purchasing power every year.
Why the loss is invisible
A savings account balance only ever goes up. Every statement confirms progress, and nothing in the account tells you that the same balance buys less than it did last year. That is the entire reason inflation is underweighted in household decisions — the counterfactual is not displayed anywhere.
₹10 lakh in a savings account for ten years
- Nominal rate
- 3.0% a year
- Inflation assumed
- 6.0% a year
- Balance after 10 years
- ₹10,00,000 × 1.03^10 ≈ ₹13,44,000
- Real return per year
- 1.03 ÷ 1.06 − 1 ≈ −2.83%
- Purchasing power after 10 years
- ₹10,00,000 × 0.9717^10 ≈ ₹7,51,000
The balance grew by ₹3.44 lakh and the purchasing power fell by roughly ₹2.49 lakh. Both statements are true, and only the first one appears anywhere the account holder can see it.
Tax first, then inflation
The order of operations matters and it is unfavourable. Tax is charged on the nominal gain, which includes the portion that only compensated you for inflation. You are therefore taxed on an increase in purchasing power you did not receive.
A deposit at a 30% slab, with 6% inflation
- Nominal rate
- 7.5%
- Post-tax nominal
- 7.5% × (1 − 0.30) = 5.25%
- Real, post-tax
- 1.0525 ÷ 1.06 − 1 ≈ −0.71%
- At a 5% slab instead
- 7.5% × 0.95 = 7.125% → 1.07125 ÷ 1.06 − 1 ≈ +1.06%
The same instrument at the same rate is mildly negative in real terms for one taxpayer and mildly positive for another. Whose money it is changes whether the investment works, which is the argument behind post-tax comparison.
ParkSmart: ParkSmart ranks short-horizon options on what you keep after tax at the slab you enter, which is the first half of this calculation done for you.
Frequently asked questions
Why not just subtract inflation from the return?
Because the relationship is multiplicative. At low rates subtraction is a good approximation — 7% nominal less 3% inflation gives 4%, and the exact figure is about 3.9%. At higher rates the gap widens: 12% less 8% suggests 4%, and the exact figure is about 3.7%. Use subtraction for a quick check and the exact formula when the numbers matter.
Should I compute the real return before or after tax?
After tax, always, and the order matters: tax is levied on the nominal gain, including the part that merely compensated for inflation. So you are taxed on money that did not increase your purchasing power. At a high slab this can turn a positive pre-tax real return into a negative post-tax one, which is the single strongest argument for comparing investments on a post-tax basis.
Does inflation affect all my expenses equally?
No, and the headline index is an average across a basket that may not resemble yours. Education and healthcare have historically risen faster than general consumer prices in India; some goods have fallen. For long-horizon planning of a specific goal, using the general rate for education costs will under-provide. Use a higher assumption where the category warrants it.
Published 2026-08-01 · Updated 2026-08-01