UK Inflation Calculator (CPI)
How the UK Inflation Calculator works
This tool uses the UK Consumer Prices Index (CPI) to estimate the change in purchasing power between two years. Enter the original yearly salary, select the year it was first offered, and choose the comparison year.
- Inflation factor = CPI(end year) ÷ CPI(start year)
- Annual inflation rate (%) = (CPI(end year) − CPI(start year)) ÷ CPI(start year) × 100
- Equivalent amount = Original amount × Inflation factor (e.g. £30,000 × 1.021 = £30,630 for 2.1%)
- Cumulative inflation = (Inflation factor − 1) × 100%
Note: CPI data is annual average with base year 2015 = 100. Figures are indicative and may differ slightly from other methodologies (e.g., monthly indices or CPIH).
We use annual UK CPI rates from the ONS series 130925 (base 2015 = 100). For the current year, we use the latest available monthly CPI annual rate as a proxy until the full-year figure is available.
We chain year-over-year CPI rates into a derived index with 2015 = 100, then compute: Adjusted amount = Original × (Index(target) ÷ Index(start)).
You can compare from 2015 (the base year) up to the current year. Annual rates are included for 2016–2024, and the current year uses the latest monthly annual rate.
This tool uses the CPI annual rate series referenced in our data file. CPIH (which includes owner occupiers’ housing costs) may differ slightly.
Figures reflect the ONS release dated 20-08-2025 for series 130925. The current year updates as new monthly values become available.
No. The tool is designed for annual comparisons. When the end year is the current year, we use the most recent monthly CPI annual rate as an interim estimate.
Indices are shown to 1 decimal place, the inflation factor to 4 decimals, currency values to 2 decimals, and cumulative inflation to 2 decimals.
No. This calculator is for guidance and educational purposes only.
Different series (CPI vs CPIH), base years, or using monthly indices instead of annual averages can lead to small differences.
