Inflation Calculator

Nominal return is the headline percentage your investment earned before considering inflation. Real return approximates how much purchasing power you gained after prices rise. A common approximation: real return ≈ nominal return − inflation rate (exact formula: (1 + nominal) ÷ (1 + inflation) − 1). If your portfolio grew 9% but inflation was 3%, your real gain is closer to 6%.

Inflation erodes the value of cash and low-yield savings. Investors compare real returns to judge whether they are actually getting ahead. The US Bureau of Labor Statistics publishes CPI, a common inflation benchmark, but you can enter any rate — personal expenses often differ from national averages.

Example: 9% nominal return, 3% inflation, over 10 years. Real return ≈ 5.8%. A purchasing power index starting at 100 might read about 176 — meaning $100 of today’s goods would cost $176 in nominal dollars after a decade at 9% growth with 3% inflation. This is a simplified model; actual CPI paths vary year to year.

Cash earning 4% nominal with 3% inflation has only ~1% real return — barely ahead. Cash at 4% with 6% inflation loses purchasing power every year even though the account balance grows.

The exact real return formula compounds both rates: real = (1 + nominal) ÷ (1 + inflation) − 1. Simple subtraction (9% − 3% = 6%) is close for small numbers but drifts over high rates or long horizons.

Purchasing power index here scales what today’s basket would cost in future nominal dollars given your inputs — useful for retirement planning conversations, not precision budgeting.

Worked example — low nominal: 5% nominal, 4% inflation → real ≈ 1.0%. Over 20 years the index shows modest nominal growth but little real gain — sequence matters for withdrawals.

TIPS and I-Bonds link returns to CPI; equities historically beat inflation over long periods but with volatility. Asset mix determines inflation protection.

Not investment advice. Future inflation is unknown — use a range of assumptions in planning.

Healthcare and education often inflate faster than headline CPI — retirees may need a higher personal inflation assumption than 2–3%.

TIPS principal adjusts with CPI — nominal return on TIPS includes inflation compensation, separate from this nominal-minus-inflation approximation.

Deflation (negative inflation) increases real returns in the exact formula — rare in modern US data but relevant for stress tests.

Social Security COLA ties to CPI-W — retirees may use SSA adjustments as a partial inflation hedge separate from portfolio return assumptions.

Hyperinflation stress tests (8–10% inflation) show how nominal “safe” returns can destroy purchasing power — useful for long retirement horizons.

Wage growth often lags CPI spikes — real wage growth requires nominal raise percentage minus inflation, parallel to investment real return math on this page.

Nominal wage growth below inflation means real income fell even when paycheck numbers rose — workers should compare raise percentage to CPI the same way investors compare nominal return to inflation.

Bundled expenses (healthcare plus housing) may inflate faster than CPI — retirees often use 4% personal inflation assumptions even when national CPI averages lower.

Real return can be negative while nominal return is positive — any period where inflation exceeds nominal investment return destroys purchasing power even when account balance grows on statements.

Budget planners sometimes add 1–2 points above CPI for conservative retirement projections — stress-test plans with higher inflation than recent averages.

Long-run financial plans often model 2%, 3%, and 4% inflation side by side — seeing a band of real outcomes beats relying on a single CPI assumption for decades-long horizons.

COLA adjustments on Social Security follow CPI-W — retirees can compare benefit bumps to personal expense inflation when judging real spending power year over year.

Stress-test retirement withdrawals with inflation one to two points above your base case to see sensitivity.

Compare real return here to wage growth — staying ahead of inflation on investments but not on income still erodes lifestyle over time.