Savings Calculators
Rule of 72 Calculator
Estimate how long money takes to double at a given rate, and the rate needed to double within a set period.
Years to double
10.3 years
- Exact doubling time
- 10.2 years
- Rate needed for your target
- 7.18%
- Value when doubled
- $50,000
Rule of 72Exact
How this calculator works
Years ≈ 72 ÷ rate
- 72
- an approximation that works well for rates between 4% and 12%
Important considerations
- The rule is an approximation — the exact figure uses logarithms.
- It applies equally to debt, which is why high-rate borrowing compounds so quickly.
Related calculators
- Compound Interest CalculatorProject the growth of a balance with compounding and regular contributions.
- Investment CalculatorProjected value of contributions and returns over time.
- Simple Interest CalculatorInterest charged on the original amount only.
- Inflation CalculatorPurchasing power of a sum over time.
- Savings Goal CalculatorMonthly saving needed to hit a target.
- Emergency Fund CalculatorEmergency fund target and time to build it.
Learn more
Terms used here
Frequently asked questions
How accurate is it?
Within a few months for typical investment returns, drifting at very high or very low rates.
Disclaimer
Legamoney calculators are educational tools. Results are estimates based on the figures you enter and do not constitute financial, tax or legal advice.
Last reviewed 2026-08-01