Inflation Rate Calculator: Measure Economic Changes Over Time
Use three numbers—recent price, earlier price, and base price—to see how much costs grew. Enter them, press calculate; the tool shows inflation as a percent. Example: recent 150, earlier 120, base 120 gives 25 % inflation. U.S. consumer prices rose 3.4 % in the year to April 2024 (BLS CPI News Release, 2024).
Inflation Rate Calculator
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How to use the tool
Bigger Year Value – type the price index for the later year. Example inputs: 150 or 210.
Smaller Year Value – enter the earlier year’s index. Example inputs: 120 or 180.
Base Year Value – supply the reference index you want to compare against; it must not be zero. Example inputs: 120 or 180.
Press “Calculate Inflation Rate” to see the percentage change instantly.
Formula used
$$
\text{Inflation Rate (\%)} = rac{\text{Bigger Year Value} – \text{Smaller Year Value}}{\text{Base Year Value}} \times 100
$$
Typical CPI index values range 0–300 (BLS CPI Handbook, 2023).
Deflation occurs when the rate is below 0 % (IMF “World Economic Outlook” 2023).
Central banks target ~2 % inflation for price stability (Federal Reserve, 2024).
A 25 % cumulative rise means today’s prices are a quarter higher than the base period (OECD Glossary, 2022).
FAQ
What does the calculator measure?
The calculator measures percentage change in a price index between two dates relative to a chosen base, reflecting inflation or deflation (OECD Glossary, 2022).
Why supply a base year?
The base year normalises results; it anchors the calculation to an agreed 100 % reference point (BLS CPI Handbook, 2023).
Can I use GDP deflators instead of CPI?
Yes. Any consistent index works; the formula is agnostic to data source (IMF, 2023).
What if my base value is zero?
Division by zero is undefined; the tool rejects zero to avoid infinite results (ISO 80000-2, 2019).
Why is my result negative?
A negative value indicates deflation — prices fell between the two years (World Bank Data Bank, 2023).
How accurate are outputs?
Outputs are exact given your inputs; data accuracy depends on the indices you enter (BLS, 2024).
How does inflation affect purchasing power?
Every 10 % inflation reduces currency purchasing power by roughly 10 % if wages stay flat (Federal Reserve, 2024).
Can I compare multiple periods?
Yes. Run the calculator for each pair of years, then compare the resulting percentages (OECD, 2022).
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