Free tool
Rule of 72 calculator
Estimate how long it takes for money to double at a given rate.
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How it works
How it works
Years to double is about 72 divided by the yearly rate. The exact figure is ln(2) divided by ln(1 + rate). Fill in either box.
FAQ
About this calculator
How accurate is the rule of 72?
It is a quick estimate that works best for rates around 6% to 10%. The exact answer is shown next to it.
Does it work for inflation or debt?
Yes. At 3% inflation, prices double in about 24 years. A balance growing at 20% doubles in about 3.6 years.
Does it include contributions?
No. It treats the starting amount only.
Is anything saved?
No. The math runs in your browser and nothing you enter is sent to us.
Is this tax or financial advice?
No. It is a calculator for general information. Check the numbers against your own records, and ask an accountant before you act on them.
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General information, not tax or legal advice. How we write and check our tools.