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Rule of 72
How long to double your money?
Years to Double
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Rule of 72: Divide 72 by your annual return rate = doubling time in years.
❓ FAQs
How does this calculator work?▼
Enter the required values and click Calculate. Results appear instantly using standard financial formulas.
Is this free?▼
Yes, completely free. No login or signup required.
Are calculations accurate?▼
Yes, industry-standard formulas. For large decisions, consult a financial advisor.
📊 What is the Rule of 72 Calculator and How Does It Work?
The Rule of 72 is a mental shortcut — divide 72 by the annual rate to get approximate doubling time in years. Works in reverse too: divide 72 by desired doubling years to find required return rate. Accurate within 1% for rates between 6–10%.
Formula
Years to double = 72 / Interest Rate% | Required rate = 72 / Years to double🪓 Step-by-Step: How to Use This Calculator
- Enter the annual interest or return rate percentage
- OR enter the number of years you want to double your money
- Click Calculate to see exact doubling time and comparison with Rule of 72
- Compare across FD, PPF, equity, and other investments
📌 Example Calculation
FD at 6.5%: doubles in 11.1 years. SIP at 12%: doubles in 6 years. PPF at 7.1%: doubles in 10.1 years. At 12%, money grows 16× in just 24 years.
✅ Benefits of Using This Calculator
- Instant mental calculation without a spreadsheet
- Compare investment options at a glance
- Understand the power of higher returns over time
- Calculate how fast inflation halves purchasing power
- Apply to debt — understand how fast high-interest debt grows
- Educate yourself and others on the power of compounding
⚙️ Key Factors That Affect Results
- Most accurate for rates between 6–10%
- Use Rule of 69.3 for continuous compounding
- Use Rule of 76 for rates above 20%
- Applies to any fixed compounding rate
- Inflation application: purchasing power halves in 72 ÷ inflation rate years
❓ Frequently Asked Questions
How accurate is Rule of 72?▼
Very accurate for 6–10% rates (under 1% error). At 20%, actual doubling is 3.8 years vs 3.6 predicted.
Can I use it for inflation?▼
Yes! At 6% inflation, purchasing power halves in 72 ÷ 6 = 12 years.
Does it work for stock market returns?▼
Approximately, using long-term averages. Nifty 50 at 12% CAGR historically doubles about every 6 years.
What is the Rule of 114?▼
Estimates time to triple your money (114 ÷ rate%). Rule of 144 estimates quadrupling.
How does it apply to debt?▼
Credit card at 36% APR: debt doubles in just 2 years if no payments are made.