The Velocity of Wealth: A mental math shortcut for estimating the power of compounding.
The Rule of 72 is the fastest mental math shortcut in personal finance. Simply divide 72 by your annual interest rate to get the approximate number of years it takes to double your money. Our calculator also works in reverse — enter a target doubling period and instantly see the required annual return.
Whether you're comparing a bank FD at 7%, PPF at 7.1%, equity SIP at 12%, or a real estate deal at 9% — the Rule of 72 lets you compare them all at a glance without a spreadsheet.
Moving from 12% to 15% ROI doesn't just add 3% profit; it reduces your doubling time from 6 years to 4.8 years—a 20% faster growth velocity.
Estimated time required to 2x your initial capital at 12% annual yield.
Precise Compounding
6.12 Years
Accurate logarithmic value.
Growth Factor
100% Boost
Capital Duplication Cycle.
The Rule of 72 assumes annual compounding. For continuous compounding, the Rule of 69 is often utilized for higher precision.
Compounding is the 8th wonder of the world. Understanding how quickly your assets double allows you to prioritize high-velocity growth opportunities over static yields.
Equities (12-15%) double money in 5-6 years, while FDs (7%) take ~10 years. This gap creates life-changing delta.
If inflation is 6%, your money's power gets halved every 12 years. You must double your money faster to survive.
Want to triple your money? Use the Rule of 114. For quadrupling (4x), use the Rule of 144.
The Rule of 72 is the fastest mental math shortcut in personal finance. Simply divide 72 by your annual interest rate to get the approximate number of years it takes to double your money. Our calculator also works in reverse — enter a target doubling period and instantly see the required annual return.
Whether you're comparing a bank FD at 7%, PPF at 7.1%, equity SIP at 12%, or a real estate deal at 9% — the Rule of 72 lets you compare them all at a glance without a spreadsheet.
The formula is deceptively simple: divide 72 by the annual interest rate. The accuracy is best between 5–15% return rates — which covers most Indian investment options.
Years to Double ≈ 72 ÷ Annual Interest Rate (%)Where:
Using Rule of 72 to instantly compare doubling time:
• Bank FD: Optimized Benchmark
• PPF: Sovereign Benchmark
• Equity Mutual Fund: Growth Benchmark
• Real Estate: Asset Benchmark
Conclusion: Equity typically doubles your money significantly faster than fixed income — a massive difference over 30 years!
At a glance — how fast different instruments double your money:
| Investment | Typical Return | Years to Double (Rule of 72) | Risk Level |
|---|---|---|---|
| Savings Account | 3-4% | 18-24 years | Negligible |
| Bank FD | 6.5-7.5% | 9.6-11 years | Very Low |
| PPF | 7.1% | ~10 years | Zero (Govt backed) |
| Debt Mutual Fund | 7-8% | 9-10 years | Low |
| Real Estate | 8-10% | 7.2-9 years | Medium |
| Equity MF (Large Cap) | 10-12% | 6-7.2 years | Medium-High |
| Equity MF (Mid/Small Cap) | 12-15% | 4.8-6 years | High |
The figures provided by this calculator are estimates based on the inputs you provide and standard financial formulas. STOCKCALC.IN does not offer investment advice. Please consult a qualified financial advisor before making any investment decisions.
Verified Contributor
I verified this calculation against the April 2026 Fiscal Cycle. If you have questions about the logic, reach out via the Author Page.
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A 12% return profile is ideal for consistent long-term wealth duplication. Your capital is growing at a healthy "wealth-building" pace.
Rule of 72 is most accurate for rates between 5% and 15%. For higher rates, the actual time to double is slightly longer than the estimate.