Calculators
Investment Doubling Calculator
How long until your money doubles? Enter a starting balance and expected annual growth rate — see the exact compounding timeline and compare it to the quick Rule of 72 estimate.
Results
Enter a starting balance and growth rate above 0% to see doubling time.
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Frequently asked questions
- How is exact doubling time calculated?
- We use the compound growth formula: years = log(2) ÷ log(1 + rate). The chart shows your balance growing toward twice the starting amount.
- Why does the Rule of 72 differ from the exact answer?
- The Rule of 72 is a linear approximation. It works best for growth rates between about 5% and 12%. Outside that range, the gap widens.
- Is this financial advice?
- No. This calculator is for educational estimates only and does not predict or recommend any investment outcome.