---
title: "Rule of 72 Calculator: Years to Double Money | RupeeCase"
description: "Rule of 72 calculator: divide 72 by the yearly return to estimate how long money takes to double, against the exact answer, with the rules of 114 and 144."
source_url: "https://www.rupeecase.com/learn/tools/rule-of-72"
---

Rule of 72: years to double**6 years**
Exact doubling time**6.1 years**ln 2 / ln(1 + r)
Value after 30 years**₹30.0 L**
Doublings in 30 years**4.90**
Rule of 114: years to triple**9.5 years**
Rule of 144: years to quadruple**12 years**

* Value

The rule is closest to the exact answer between about 6% and 10% a year; at 12.0% it is off by 0.1 years.
      Share this resultReset

  01How it works

## In plain words.
The exact doubling time is ln 2 divided by ln(1 + r). For everyday rates that is close to 0.72 divided by r, so 72 divided by the rate in percent gives the years. The same trick gives tripling (114) and quadrupling (144) times.

    The formula

`Years to double, rule: 72 / r``Years to double, exact: ln 2 / ln(1 + r)``Tripling: 114 / r; quadrupling: 144 / r`

  02Worked example

## The default numbers, by hand.
At 12% a year: 72 / 12 = 6 years; the exact answer is ln 2 / ln 1.12 = 6.1 years. Over 30 years that is about 4.9 doublings: Rs 1 lakh becomes about Rs 30 lakh.

| Input | Value |
| --- | --- |
| Return a year | 12% |
| Amount | ₹1,00,000 |
| Horizon | 30 years |

| Result | Value |
| --- | --- |
| Rule of 72: years to double | 6 years |
| Exact doubling time | 6.1 years |
| Value after 30 years | ₹30.0 L |
| Doublings in 30 years | 4.90 |
| Rule of 114: years to triple | 9.5 years |
| Rule of 144: years to quadruple | 12 years |

  03Key concepts

## What to know before you use it.

### It works for anything that compounds
Prices at 6% inflation double in about 12 years. A credit card balance at 36% a year doubles in about 2 years.

### Where it is accurate
The rule is closest between about 6% and 10%. At 1% or 25% use the exact figure on the right.

### Good to know

* Compare doubling times instead of rates: 9.8% (the Nifty 50 TRI figure on this page, with its date) doubles in about 7.4 years; a 7% deposit assumption in about 10.2 years.
* The number of doublings, not the rate, is what makes long horizons so different.

  04Assumptions

## What the calculator assumes.

* A constant compound rate.

  05Questions

## Asked about the Rule of 72.
What is the rule of 72?A shortcut: 72 divided by the yearly percentage rate gives the approximate years for money to double. At 8% that is 9 years.

How accurate is the rule of 72?Within a few months between about 6% and 10%. The exact doubling time is ln 2 / ln(1 + r).

What are the rules of 114 and 144?The same shortcut for tripling (114 / r) and quadrupling (144 / r).

    Explore next

## Learn the idea behind the numbers.

* [Blog noteRule of 72: count in doublingsReturns and risk maths, a short note](/blog/2026-07-14-evening-doubling-clock/)
* [Blog noteThe minimum due trapPersonal finance and tax, a short note](/blog/2026-07-10-evening-minimum-due-trap/)
* [Free module 1.1How Indian Stock Markets Work12 min read](/learn/path-1/module-1-1-how-indian-stock-markets-work)
* [Free module 7.3Inflation, Types, Measurement, and Investment Impact10 min read](/learn/path-7/module-7-3-inflation-types-measurement-investment-impact)
* [StrategyNifty 50 Equal Weight strategyNifty 50, 50 stocks, every 4 weeks](/strategies/nifty-50-equal-weight)
* [CalculatorSIP calculatorFree, with the formula and a worked example](/learn/tools/sip-calculator)

      Community

## Join my WhatsApp group.

      Scan the code, fillFill one short form, and join my WhatsApp group. Slides, sources, factsheets and the rebalance logs live there, and members join a daily Google Meet with me.

        [Sign up for RupeeCase](https://invest.rupeecase.com/signup)
        [Join the WhatsApp group](https://forms.gle/C6HMtM1Z2GfeocQV7)

      [One form, one group](https://forms.gle/C6HMtM1Z2GfeocQV7)Scan with your phone camera

06Keep going

## Learn the idea, see it applied.

  [Module 1.1How Indian Stock Markets Work12 min read, Path 01](/learn/path-1/module-1-1-how-indian-stock-markets-work)[Module 7.3Inflation: Types, Measurement, and Investment Impact10 min read, Path 07](/learn/path-7/module-7-3-inflation-types-measurement-investment-impact)[The matching indexNifty 50 Equal WeightAll 50 Nifty names, equal weight. The simplest card on the lineup.CAGR16.4%Sharpe1.13Max DD−15.7%Model, back tested, as of 27 Apr 2026. Not client returns, not a promise. Risk band: Moderate.](/strategies/nifty-50-equal-weight)

  More returns and compounding calculators

[SIP calculator](/learn/tools/sip-calculator)[Step up SIP calculator](/learn/tools/step-up-sip-calculator)[Lumpsum calculator](/learn/tools/lumpsum-calculator)[All 25 calculators](/learn/tools)

  Education only, not investment advice. RupeeCase is a technology platform operated by QC Alpha Technologies Pvt Ltd; it is not a fund, a PMS or a SEBI registered investment adviser. Model returns are back tested and not a promise of future returns. Figures carry the date they were checked.