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Inflation Calculator

Projects how an amount's cost rises and its purchasing power falls over a number of years at a constant annual inflation rate, using compound growth of the price level.

When to use

You want to estimate what today's amount will cost in the future, or what a future sum is worth in today's money, from an assumed inflation rate.

Do not use when: You need historical conversions between two calendar years (that requires a CPI table such as the BLS inflation calculator), or investment discounting (use present-value).

Formula

multiplier = (1 + annual_inflation_percent/100)^years; future_cost = amount × multiplier; purchasing_power = amount / multiplier; cumulative_inflation = (multiplier − 1) × 100

Rate-based projection with a single constant rate compounded annually; it does not use actual CPI data and real inflation varies year to year and by basket of goods.

Inputs

Parameter	Type	Unit	Required	Description
`amount`	number		yes	Amount in today's money. Range: ≥ 0, ≤ 1000000000000000
`annual_inflation_percent`	number	%	yes	Assumed constant yearly inflation in percent (negative for deflation). Many central banks target about 2 %. Range: ≥ -50, ≤ 200
`years`	number	years	yes	Number of years ahead. Range: > 0, ≤ 200

Outputs

Output	Type	Unit	Description
`future_cost`	number		amount × (1 + inflation)^years: nominal money needed later to buy what amount buys today.
`purchasing_power`	number		amount / (1 + inflation)^years: what the same nominal amount will buy, in today's money.
`cumulative_inflation_percent`	number	%	((1 + inflation)^years − 1) × 100, total price-level rise.
`purchasing_power_loss_percent`	number	%	(1 − 1 / (1 + inflation)^years) × 100.
`price_multiplier`	number		(1 + inflation)^years.

Example

1,000 at 3 % for 10 years: {"amount":1000,"annual_inflation_percent":3,"years":10} → {"future_cost":1343.92,"purchasing_power":744.09,"cumulative_inflation_percent":34.39,"purchasing_power_loss_percent":25.59,"price_multiplier":1.3439}

50,000 at 2 % for 20 years: {"amount":50000,"annual_inflation_percent":2,"years":20} → {"future_cost":74297.37,"purchasing_power":33648.57,"cumulative_inflation_percent":48.59}

GET https://tttkmbb.com/api/v1/calculate/inflation?amount=1000&annual_inflation_percent=3&years=10

Machine access

API: GET https://tttkmbb.com/api/v1/calculate/inflation (query parameters) or POST with a JSON body {"inputs": {...}}
Schema: https://tttkmbb.com/api/v1/calculators/inflation · Markdown: https://tttkmbb.com/finance/inflation.md · JSON definition: https://tttkmbb.com/finance/inflation.json
MCP: server https://tttkmbb.com/mcp, tool run_calculator with calculator_id="inflation"
OpenAPI operationId: estimate_inflation_impact
Freshness: static. Authentication: none. Rate limit: fair use (see rate limits).

Sources

U.S. Bureau of Labor Statistics – CPI Inflation Calculator (historical conversions) (government)
Federal Reserve – Why does the Federal Reserve aim for inflation of 2 percent over the longer run? (government)
Wikipedia – Inflation (reference)

FAQ

Which output do I want?

future_cost answers 'how much will this cost in N years'; purchasing_power answers 'what will this nominal amount be worth in N years'. They are reciprocal projections of the same rate.

Why is the purchasing-power loss smaller than the cumulative inflation?

Because a 34.39 % rise in prices reduces what a fixed amount buys by 1 − 1/1.3439 = 25.59 %; the two measure the same change from opposite sides.

Related calculators

Present Value Calculator — Discount a future amount at an investment rate instead of inflation.
CAGR Calculator — Find the implied annual rate between two price levels.