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Real return calculator

See the difference between what your account shows and what your money is actually worth — inflation silently erodes nominal returns over long horizons.

Logic updated April 2026

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This calculator projects investment growth on two parallel paths: the nominal balance (what your statement will say) and the real balance (what that money is actually worth in today's purchasing power, after inflation). For long-horizon planning, real returns are the only honest comparison — a 7% nominal return in a 3% inflation environment is a 4% real return, which is what determines whether you're actually getting wealthier.

How this is calculated

Formula

realRate = ((1 + nominal/100) / (1 + inflation/100) − 1) × 100 ; balance(year) = (balance + annualContribution) × (1 + rate/100)

Step-by-step

Compute the real rate using the Fisher equation: ((1 + nominal/100) ÷ (1 + inflation/100) − 1) × 100
For each year, add the annual contribution (monthly × 12) to the start-of-year balance
Multiply the post-contribution balance by (1 + rate/100) to get the end-of-year balance
Run two parallel paths: one using the nominal rate, one using the real rate
Track both balances year by year — the gap between them is the inflation-eroded purchasing power
End-of-horizon comparison: nominal balance minus real balance equals the dollar value lost to inflation in real terms

Rounding mode: ROUND_HALF_UP
Precision: 20-digit internal precision (Decimal.js), rounded to 2 decimal places for display
Logic last reviewed: 2026-04-30

Assumptions & limitations

What this calculator assumes

Nominal returns and inflation rates are held constant over the horizon
Monthly contributions are added at the start of each month, compounded annually
Real values are expressed in today's purchasing power (year-0 dollars)
Taxes, fees, and currency exchange are not modelled

What this calculator doesn’t account for

Constant inflation is a simplification — real inflation is variable, and high-inflation episodes can dramatically erode purchasing power
Nominal return is treated as constant — real markets are volatile
Doesn't model the relationship between inflation and nominal returns (in real life they're partly correlated)
Doesn't account for sequence-of-returns risk if withdrawing during the horizon
Doesn't model jurisdiction-specific tax effects on investment returns

Worked example

An investor with $50,000 contributes $500/month for 30 years at an 8% nominal return, with 3% expected long-run inflation.

Input	Value
Initial investment	$50,000
Monthly contribution	$500
Investment horizon	30 years
Nominal return	8%
Inflation rate	3%

Real rate: ~4.85% — Nominal end balance: ~$1.20M — Real end balance: ~$510k

Nominal: starting at $50k, adding $6,000/year, growing at 8%, the balance reaches approximately $1.20 million. But $1.20 million in 30-year-future dollars buys what $510,000 buys today — that's the real (inflation-adjusted) end balance. The $690,000 'gap' is the purchasing power that inflation will silently take from the headline figure. For retirement planning, $510k in today's dollars is the honest number.

Frequently asked questions

What is a real return?

The investment return after subtracting inflation — the rate at which your purchasing power actually grows. If your portfolio earns 7% (nominal) but inflation is 2%, your real return is approximately 5% — that's the real-world increase in what you can buy with the portfolio. Nominal returns sound bigger; real returns are what matter for long-term planning.

How does inflation erode investment gains?

Inflation reduces the purchasing power of every dollar over time. At 3% inflation, today's $100 buys what $74 buys in 10 years and what $41 buys in 30 years. So a portfolio that doubles in nominal terms over 30 years (which sounds great) only buys 0.82× what the original sum bought, in inflation-adjusted terms — you've actually lost purchasing power. Long-horizon nominal returns must clear inflation by a meaningful margin to grow real wealth.

Fisher equation explained?

Named after economist Irving Fisher, it's the equation that converts nominal returns to real returns: (1 + nominal) = (1 + real) × (1 + inflation). Rearranging: real = ((1 + nominal) ÷ (1 + inflation)) − 1. The simple subtraction (real ≈ nominal − inflation) is a good approximation at low rates but breaks down at high inflation; this calculator uses the exact formula.

Why do financial planners use real returns?

Because retirement and long-horizon goals are framed in today's purchasing power — 'I need $50,000 a year to live on'. To plan for that, you need to know how much real wealth your investments will produce, not how big the headline balance will be in 30-year-future dollars. Using real returns and real contributions makes the entire plan internally consistent in today's purchasing power.

What inflation rate should I assume?

Most developed-economy long-run averages are 2–3%, which is also where most central banks target. For planning, using 2.5% or 3% is reasonable for a baseline; consider running the calculator at 4% as a stress test in case inflation is structurally higher than recent decades. If you live in a high-inflation jurisdiction, use your local long-run average — the calculator handles any positive inflation rate.

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