# 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.

- Calculator id: `inflation` · Category: Finance (`finance`) · Tool name: `estimate_inflation_impact`
- Canonical page: https://tttkmbb.com/finance/inflation · This document: https://tttkmbb.com/finance/inflation.md · JSON definition: https://tttkmbb.com/finance/inflation.json

## Purpose

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.

**Use when:** 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).

## Input

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

## Output

| Field | 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. |

## 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.

## Data Sources

- U.S. Bureau of Labor Statistics – CPI Inflation Calculator (historical conversions) — https://www.bls.gov/data/inflation_calculator.htm (government, retrieved 2026-09-23)
- Federal Reserve – Why does the Federal Reserve aim for inflation of 2 percent over the longer run? — https://www.federalreserve.gov/faqs/economy_14400.htm (government, retrieved 2026-09-23)
- Wikipedia – Inflation — https://en.wikipedia.org/wiki/Inflation (reference, retrieved 2026-09-23)

Data freshness: `static`. Deterministic formula with fixed constants; results never go stale. Inputs supplied by the caller determine the output.

## API

- `GET https://tttkmbb.com/api/v1/calculate/inflation?amount=…&annual_inflation_percent=…&years=…`
- `POST https://tttkmbb.com/api/v1/calculate/inflation` with JSON body `{"inputs": {…}}`
- Response: unified envelope (`success`, `request`, `result.values`, `result.units`, `sources`, `freshness`, `timestamp`, `next_actions`, `links`); see https://tttkmbb.com/docs/response-format.md
- Schema: https://tttkmbb.com/api/v1/calculators/inflation · OpenAPI operationId `estimate_inflation_impact` in https://tttkmbb.com/openapi.json
- Authentication: none. Rate limit: fair use, see https://tttkmbb.com/docs/rate-limits.md.

## MCP

- Server: `https://tttkmbb.com/mcp` (Streamable HTTP, JSON-RPC 2.0, no auth)
- Tool:  `run_calculator` with `{"calculator_id": "inflation", "inputs": {…}}`

## Example

- 1,000 at 3 % for 10 years: inputs `{"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: inputs `{"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
```

## Limitations

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). 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. All values are computed from the formula above; no measurement or live data is involved.

## 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

- [Present Value Calculator](https://tttkmbb.com/finance/present-value.md) — Discount a future amount at an investment rate instead of inflation.
- [CAGR Calculator](https://tttkmbb.com/finance/cagr.md) — Find the implied annual rate between two price levels.