Rule of 72 Calculator

The rule of 72 is the fastest way to estimate doubling time: divide 72 by your annual rate. Enter a rate below to get the estimate, the exact doubling time and a quick table of how your money grows.

Tool Features

• Rule of 72 doubling estimate
• Exact doubling time from the true formula
• Growth table at each doubling
• See how small rate changes matter
• No registration or software installation

Common Usage

• Sanity-check a return assumption
• Show a kid how compounding works
• Compare savings vs investment rates
• Estimate when a sum will double