# Rule of 72 Calculator: Years to Double Your Money > Rule of 72 calculator: divide 72 by the return to see how many years money takes to double, or the return needed in a set time, with exact figures. Source: https://trykosh.com/tools/rule-of-72-calculator Free tool - Investing # Rule of 72: how long to double your money Divide 72 by the yearly return and you get roughly how many years it takes money to double. Check the shortcut against the exact answer here. Rules checked 25 October 2026Free - no sign-upRuns in your browser Years to double (rule of 72) 8.0 years 72 / 9 = 8.00 Exact answer**8.04 years** To triple (rule of 114)**12.7 years** To grow 4x (rule of 144)**16.0 years** Doubling and tripling at common rates Return Rule of 72 Exact doubling Tripling (rule of 114) 4% 18.0 years 17.7 years 28.5 years 6% 12.0 years 11.9 years 19.0 years 7.1% 10.1 years 10.1 years 16.1 years 8% 9.0 years 9.0 years 14.3 years 10% 7.2 years 7.3 years 11.4 years 12% 6.0 years 6.1 years 9.5 years 15% 4.8 years 5.0 years 7.6 years 18% 4.0 years 4.2 years 6.3 years The shortcut is off by 0.04 years here. It's most accurate between 6% and 10%. ## Upload your statement and Kosh does this for you. Upload your statements and Kosh tracks every SIP, FD and deposit in one place, and shows how far you are from each goal. [Start free](/signup?via=tool-rule-of-72-calculator) ## How the rule of 72 calculator works The rule of 72 is a mental shortcut for compounding. At 8% a year, money doubles in about 72 / 8 = 9 years. At 12%, about 6 years. It works in reverse too: to double in 6 years, you need about 72 / 6 = 12% a year. The exact doubling time is the natural log of 2 divided by the log of (1 + rate). The rule of 72 is very close for rates between about 6% and 10% and drifts a little at very low or very high rates. The calculator shows both. The same idea extends to other multiples. Divide 114 by the rate to estimate the years to triple, and 144 to estimate the years to quadruple. It applies to anything that compounds: investments, inflation (at 6%, prices double in about 12 years) and debt (at 36% credit card interest, a balance doubles in about 2 years). Years to double ~= 72 / rate; exact = ln 2 / ln(1 + rate / 100) ## Worked example: How long does PPF take to double? Kiran wants to know how long money in PPF takes to double at the current 7.1%. The rule of 72 says about 10.1 years; the exact answer is 10.11 years. To triple it would take about 16.1 years, a little longer than PPF's 15-year term. Years to double (rule of 72) 10.1 years 72 / 7.1 = 10.14 Exact answer**10.11 years** To triple (rule of 114)**16.1 years** To grow 4x (rule of 144)**20.3 years** The shortcut is off by 0.04 years here. It's most accurate between 6% and 10%. [Load this example into the calculator ->](?rate=7.1#calculator) ## Good to know - Use the rule to sense-check promises. A scheme claiming to double your money in 3 years is implying 24% a year, far above what safe investments pay. - Apply it to inflation to see how fast your expenses double: 72 / 6% is 12 years. - Some people use 69 or 70 for continuous compounding or low rates. For everyday Indian rates, 72 is the handiest. ## Frequently asked questions What is the rule of 72? It's a shortcut: divide 72 by the yearly return to estimate how many years money takes to double. At 9% it takes about 8 years. How accurate is the rule of 72? Very accurate between about 6% and 10%, typically within a few weeks. At 18% it says 4 years against an exact 4.19, and at 2% it says 36 against an exact 35. In how many years will money double at 7% interest? About 72 / 7 = 10.3 years. The exact figure is 10.24 years with yearly compounding. What is the rule of 114 and 144? They extend the same idea. Divide 114 by the rate to estimate the years to triple, and 144 to estimate the years to quadruple your money. ## Sources and assumptions - [Department of Economic Affairs: small savings rates](https://dea.gov.in/) Rules and rates last checked on 25 October 2026. Results are estimates for planning and education, not tax, legal or investment advice. Kosh is an educational financial planning tool by Primedepth Labs. It is not a SEBI-registered investment adviser and does not offer personalised investment advice, hold your money or execute trades. Markets carry risk; read scheme documents carefully and consult a registered adviser before acting.