Inflation, Real Returns and Retirement Money

Two ways to describe the same future balance

A future statement shows nominal money: the currency amount in the account. Today’s-money values describe purchasing power relative to current prices. Neither is inherently more correct, but comparing one with the other without conversion can create a false surplus or shortfall.

At 3% annual inflation, 2,000 of current monthly spending becomes approximately 3,612 after 20 years. Conversely, 100,000 received after 20 years has purchasing power of approximately 55,368 today. These are mathematical illustrations using constant inflation, not forecasts.

Use the exact annual relationship

The real annual return is (1 + nominal return) / (1 + inflation) − 1. Rates are decimals in the formula. A 6% nominal return and 3% inflation give about 2.913% real return. Simply subtracting inflation gives a close approximation at small rates, but it is not exactly the same calculation.

Fees and taxes can reduce the nominal return available to the investor. Decide whether the return is gross or net before adjusting for inflation. Subtracting an expense already reflected in a published fund return would count the same cost twice.

Contributions also have a purchasing-power basis

A fixed nominal monthly deposit becomes smaller in real terms as prices rise. A contribution that increases at the inflation rate approximately preserves its purchasing power. Contribution growth and investment growth are separate: one changes the money you add; the other changes the money already invested.

The main retirement calculator increases nominal contributions at the entered annual rate, converts the change relative to inflation, and applies that real contribution pattern to the projection. The extra-saving result follows the same growth pattern. Specialist tools usually use level nominal deposits unless stated otherwise.

Pensions are not all inflation-linked

A pension that pays a fixed nominal amount buys less over time. A payment linked to an index can behave differently, and a capped increase may still lag actual household costs. Read the scheme’s adjustment rule before assuming a pension remains constant in today’s purchasing power.

The main retirement model assumes that entered outside income remains constant in real terms and starts at retirement. For a fixed nominal or delayed pension, that simplification can overstate income. Use separate planning phases or a more detailed cash-flow model for a consequential decision.

Why calculators can disagree

One calculator may divide an annual rate by 12, while another derives an effective monthly rate using (1 + annual rate)^(1/12) − 1. The same percentage entered under different conventions produces slightly different growth. Contributions at the beginning rather than end of a month also change the result.

Before comparing two outputs, align deposit timing, inflation basis, tax treatment, fees and whether the target assumes an ending balance of zero. A disagreement is not proof that one tool is incorrect; it can indicate different conventions.

A practical check before accepting a result

Label every figure as current money or future money. Check whether contributions are level or increasing. Check whether the stated return already deducts costs, and whether income starts immediately or later. Finally, test higher inflation without increasing the return simply to offset it.

Use the main retirement calculator to compare today’s and retirement-date money. The future-value calculator provides a nominal projection. See the methodology for the conventions implemented by this theme.