Rule of 72 Calculator
Estimate years to double your money at any annual return rate — and the reverse.
100% client-side · no upload
Years to Double (at given rate)
Rate Required to Double in N years
How to use
- Enter an annual return rate to see how many years it takes to double your money.
- Enter a target number of years to see what annual return rate is required.
- The Rule of 72 is an approximation — most accurate between 6% and 10% annual rates.
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Frequently Asked Questions
- Is this Rule of 72 calculator free?
- Yes, completely free with no signup required. All calculations run in your browser.
- Does my data leave my device?
- No. The calculator runs entirely in your browser with no data sent to any server.
- Does it work on mobile?
- Yes. The tool is mobile-first and works on iPhone Safari and Android Chrome.
- How accurate is the Rule of 72?
- Very accurate between 6% and 10%. It slightly underestimates doubling time at very low rates and overestimates at very high rates. For exact results use the full formula: t = ln(2) / ln(1 + r).
- Can I use the Rule of 72 for inflation?
- Yes. At 3% inflation, purchasing power halves in 72/3 = 24 years. At 7% inflation, it halves in about 10 years — this is why investments must beat inflation.
Last updated: By jarvisbox