Rule of 72 Calculator
Estimate how many years it takes money to double.
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How it works
Rule of 72: years to double ≈ 72 ÷ annual rate. The exact value uses ln(2) ÷ ln(1 + rate).
FAQ
Is this calculator free?
Yes. No signup is needed and nothing you enter is stored.
Is the result exact?
Results are rounded for display. For financial, medical, or legal decisions, confirm with a professional.
Do my numbers leave my device?
No. The calculation runs in your browser.