Rule of 72 Calculator
Estimate how many years it takes money to double at a given return — or the return needed to double in a set time.
Years to double (rule of 72)
9
- Exact years
- 9.00647
- Rule of 70
- 8.75
- Rule of 69.3
- 8.6625
The rule of 72 is most accurate for rates between about 6% and 10%.
Show the work
Exact doubling time, for comparison
years = ln 2 ÷ ln(1 + rate ÷ 100)
ln 2 ÷ ln(1 + 8 ÷ 100) = 9.00647
Rule of 72 estimate
years ≈ 72 ÷ rate
72 ÷ 8 = 9
Estimates for general information only — not financial advice.
How it works
Years to double ≈ 72 ÷ rate (%); exact = ln 2 ÷ ln(1 + rate)
Questions
- How does the rule of 72 calculator work?
- Years to double ≈ 72 ÷ rate (%); exact = ln 2 ÷ ln(1 + rate).
- What do I need to enter?
- Find, Annual rate, Years to double. Optional fields can be left blank.
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