Free financial calculator
Rule of 72 Calculator
Estimate how long it could take money to double at a fixed annual return.
Use the calculator ↓Adjust the assumptions
Rule of 72 Calculator
Estimate how long it could take money to double at a fixed annual return.
Result
£0
View year-by-year breakdown ＋
| Year | Contributions | Growth | Balance |
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Questions answered
What this calculator helps you work out
- How long could it take my money to double?
- What return would produce a faster doubling time?
- How close is the Rule of 72 to the exact result?
Common questions
Rule of 72 Calculator FAQs
Why is the number 72 used?＋
It is conveniently divisible and gives a close mental estimate across many common interest rates.
Is the Rule of 72 exact?＋
No. It is an approximation, so the calculator also reports the exact compound result.
Can I use it for inflation?＋
Yes. Dividing 72 by an inflation rate estimates how long prices could take to double if that rate persisted.