This inflation calculator answers a different question than a simple rate-projection tool: what did money actually lose (or gain, working backward) using real historical CPI data where it’s available, alongside flat-rate projections for planning forward or backward at a constant assumed rate. Four modes cover the full range, from historically grounded calculations to simple flat-rate math.

How to use this inflation calculator

1. Select your Currency, or add a custom one.
2. Choose a tab: Simple Calculator, Historical CPI Lookup, Forward Flat Rate, or Backward Flat Rate.
3. Simple Calculator: enter an Initial Amount, Start Year, End Year, and Average Annual Inflation Rate, or pick a Quick Preset (India 6%, USA 3.5%, EU 2.5%, UK 2.8%).
4. Historical CPI Lookup: enter an Amount, a From Year, and optionally a To Year (defaults to the latest available year), using real historical CPI data for your selected currency where available.
5. Forward Flat Rate: enter an Initial Amount, Annual Inflation Rate, and Years to project a future equivalent value at a constant rate.
6. Backward Flat Rate: enter a Current Amount, Annual Inflation Rate, and Years Ago to find the equivalent purchasing power some years in the past.
7. Review your results and the Year by Year Breakdown (Simple tab), and export as PDF, Excel, or PNG.
8. Check View History for past calculations across any tab.

What this inflation calculator does

The four tabs split into two fundamentally different approaches: the Simple Calculator and Historical CPI Lookup work from real, dated inflation figures (or a rate you set for a specific year range), while Forward and Backward Flat Rate apply a single constant rate assumption over any number of years without reference to specific calendar years at all. Choosing the right tab depends on whether you’re asking about a specific historical period or just modeling a generic constant-rate scenario.

Simple Calculator: a specific year range

This tab projects an amount from a Start Year to an End Year using your chosen Average Annual Inflation Rate, and includes country-specific Quick Presets (India, USA, EU, UK) as reasonable starting rate assumptions if you don’t have a specific figure in mind. The Year by Year Breakdown table shows the value, inflation added, cumulative change, and purchasing power for every single year in your range, not just the final result, useful for seeing exactly how the erosion accelerates or compounds across the full period.

Historical CPI Lookup: real data instead of an assumption

This is the tab that sets this calculator apart from a purely assumption-based tool. Rather than requiring you to guess at a rate, it uses real historical CPI (Consumer Price Index) data bundled for the selected currency where available, calculating the actual cumulative inflation and average annual rate that occurred between your From Year and To Year. If bundled CPI data isn’t available for a particular currency, the calculator falls back to asking for an Average Annual Inflation Rate manually, and flags this explicitly rather than silently substituting a guess.

Forward and Backward Flat Rate: constant-rate projections

These two tabs are the simplest and most direct: Forward projects an Initial Amount into the future at a constant Annual Inflation Rate over a set number of Years, while Backward works in reverse, taking a Current Amount and finding its equivalent purchasing power a set number of Years Ago at that same constant rate.

Neither tab references specific calendar years or historical data, they’re pure constant-rate math, useful for quick planning scenarios (“what would $10,000 be worth in 15 years at 3% inflation?”) without needing to anchor the calculation to real historical dates.

Choosing between historical data and a flat rate

A note on accuracy and appropriate use

Historical CPI figures used by this calculator are approximate annual averages reconstructed from public sources, provided for estimation only. They are explicitly not intended for legal, tax, or contractual indexation use, situations that require officially published, audited CPI figures from a government statistical agency, not a reconstructed approximation from a general-purpose calculator. Flat-rate projections (Forward and Backward tabs) are purely theoretical and assume a constant rate that real inflation never actually follows exactly. Currency selection changes only the displayed symbol and formatting; no live exchange-rate conversion is performed.

Frequently asked questions