Guide·Updated October 20, 2026

Inflation and Real Returns: The Number That Actually Buys Things

A 7% return during 3% inflation is not 7%. Here is the arithmetic that turns nominal returns into purchasing power, and why it changes every retirement target.

Nominal vs. Real Returns

A nominal return is the number on your statement: the percentage your balance grew in dollars. A real return is that growth after inflation, the percentage gain in what your money can actually buy. Your rent, groceries and invoices are paid in today's prices, so the real return is the one that matters. Inflation is not theoretical. The Bureau of Labor Statistics reported that the Consumer Price Index rose 3.7% over the 12 months ending September 2026, well above the Federal Reserve's 2% longer-run goal, which it measures with the PCE price index. At that rate, an account earning 3.7% has gone nowhere in real terms.

The Fisher Equation

The quick version, known as the Fisher approximation, is real return ≈ nominal return − inflation. The exact version is real = (1 + nominal) ÷ (1 + inflation) − 1. With 7% nominal and 3% inflation, the shortcut says 4%; the exact answer is 1.07 ÷ 1.03 − 1 = 3.88%. The difference looks small, but compounding magnifies it, and it grows as rates rise. A related trap: tax is charged on nominal gains. A savings account paying a hypothetical 5% is worth 3.8% after a 24% federal tax rate, and against 3.7% inflation that is a real return of about 0.1%. After tax and inflation, a high-yield account protects purchasing power; it does not grow it.

A Worked Example

Invest $500,000 for 30 years at 7% nominal. The statement will eventually show $3,806,128. Deflate that by 3% a year and it is worth $1,568,074 in today's dollars, still a good result but well under half the headline figure. Using the 4% Fisher shortcut instead of the exact 3.88% would give $1,621,699, overstating your real wealth by $53,625. The same arithmetic works in reverse. At 3% inflation, $100,000 held in cash for 20 years buys what $55,368 buys today. Rule of 72: at 3% inflation, prices double roughly every 24 years, well within a typical retirement.

Why It Changes Your Retirement Target

A target stated in today's dollars and a projection stated in future dollars cannot be compared. If you spend $60,000 a year today, the 25× rule puts your number at $1.5 million in today's dollars. In 25 years, at 3% inflation, the same lifestyle costs $125,627 a year, and 25× of that is $3,140,667 in the dollars your future statements will show. Neither figure is wrong; mixing them is. Either project everything in real terms, with real returns against today's spending, or everything in nominal terms. The common mistake is to project a nominal 7% balance against today's spending, which makes you look decades closer to retirement than you are.

Protecting Purchasing Power

Over long horizons, only assets with real growth have reliably outpaced inflation: diversified equities and real assets, and, for the safe portion of a portfolio, inflation-indexed bonds such as TIPS and I bonds, whose principal or rate adjusts with CPI. Cash is for stability and liquidity, not for long-term growth. In planning, use an inflation assumption you can defend. The Fed's 2% target is a reasonable long-run anchor, and the recent 3.7% CPI print is a reasonable stress case. Re-run your plan when actual inflation moves away from it, because a single year of 3.7% inflation raises every later year's costs from a higher base.

Put This Into Practice

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Frequently Asked Questions

What is the difference between nominal and real return?

Nominal return is the percentage growth in dollars. Real return is that growth after inflation, meaning the growth in what your money can buy. The exact formula is (1 + nominal) ÷ (1 + inflation) − 1; subtracting inflation from the nominal return is a close approximation at low rates.

What real return should I assume for retirement planning?

Take your nominal return assumption and convert it with your inflation assumption, rather than picking a real number directly. For example, 7% nominal with 3% inflation is 3.88% real. Test a stress case too, using higher inflation or lower returns, before you rely on the result.

Is a high-yield savings account beating inflation?

Often not after tax. Interest is taxed as ordinary income on the nominal amount, so a 5% yield in the 24% bracket nets 3.8%, roughly break-even against the 3.7% CPI increase reported for the 12 months to September 2026. Use savings accounts for liquidity, not growth.

Does the 4% rule account for inflation?

Yes. The 4% rule means withdrawing 4% of the portfolio in year one, then raising the dollar amount with inflation each year. The research behind it was built on historical real returns, which is why it pairs with a target stated in today's dollars.

Sources

Limits and thresholds change every year. Confirm against the current publication.