Useful next calculations
Rates and sources
Purchasing-power illustration using the inflation rate you enter. UK CPI is published by the ONS; this page does not forecast inflation or mortgage rates.
Source: ONS — Inflation and price indices. Check the linked guidance and any live quote before acting.
When to use this calculator
- When you want to see how a published inflation rate changes the real value of a sum of money.
- When you are comparing a cash amount today with the same amount in a past or future year.
- When you need a purchasing-power illustration alongside a savings or investment projection.
- When you want to convert a historic price into today’s money using a CPI-style rate.
A worked example
These are the example figures the calculator opens with.
| Input | Value |
|---|---|
| Starting Amount (£) | £10,000 |
| Annual Inflation Rate (%) | 3% |
| Years | 10 |
For those figures the calculator returns:
- Future Equivalent: £13,439.16
- Today Amount: £10,000.00
- Purchasing Power Loss: £3,439.16
- Real Value Today: £7,440.94
Method & assumptions
This calculator applies compound inflation to convert a sum of money between two points in time. Enter a published consumer price index (CPI) or equivalent annual rate for the country the cash amount belongs to. When a rate is entered, the tool applies that rate consistently across every year in the range, which is a simplification — official inflation fluctuates year to year. The result is a purchasing-power illustration, not a forecast of prices, wages, investment returns or borrowing costs.
Common mistakes
- Entering a mortgage or savings rate instead of an inflation index such as CPI.
- Treating the result as a Bank of England forecast or a lender stress test.
- Forgetting that CPI and CPIH (and RPI) are different series.
- Applying a UK inflation series to a non-UK cash amount without saying so.
What to do next
- Use a published ONS CPI figure rather than a mortgage or savings rate.
- Compare the real value with a savings-growth or investment-return scenario if you are planning a future purchase.
- Rerun with a higher inflation assumption as a caution case.
- Do not use this page as a substitute for a Bank of England or lender forecast.