Inflation Calculator
Enter an amount and a month. We estimate what that money is worth today by applying UK inflation across the years using official ONS price indices. Choose CPIH, CPI or RPI, or use Best available (recommended).
Your inputs
Best available automatically picks the most suitable dataset for your chosen month (CPIH, then CPI, then RPI).
Result
UK inflation indices explained
Inflation indices are official measures of how prices change over time. If an index rises, that usually means the same basket of goods and services costs more than it did before. This calculator converts a past amount into a “today equivalent” by comparing the index in your chosen month with the latest available month in the same dataset.
Which dataset should you use?
- CPIH is CPI plus owner occupiers’ housing costs and Council Tax. It is often described as the ONS’s most comprehensive inflation measure.
- CPI is a widely used consumer inflation measure, commonly used for comparisons and some contracts.
- RPI is an older measure. It is still used in some contexts, but it is not the ONS’s preferred headline measure.
- Best available selects the best covered dataset for your chosen month so you can go further back in time.
How the calculation works
We use a simple index ratio:
- Value today = amount × (index in latest month ÷ index in chosen month)
- Cumulative inflation = (index in latest month ÷ index in chosen month − 1) × 100%
Coverage and limitations
Different datasets cover different time ranges. If you pick a dataset that does not include your chosen month, we will show an error and tell you the date range that dataset supports.
This tool is for general information. It does not include investment returns, property specific effects, regional house prices, taxes, or individual spending patterns.
Data sources
Data is sourced from Office for National Statistics (ONS) time series data and refreshed automatically by SimplyCheck. The site stores a local snapshot in JSON for speed and reliability.