Rule of 72 Calculator India — How Long to Double Your Money?
Year-wise Growth · Contributions · Inflation Adjusted · Goal Planner
Rule of 72: divide 72 by your annual interest rate to get the approximate years to double your money. PPF at 7.1% → doubles in 10.1 years. Equity MF at 14% → doubles in 5.1 years. FD at 7% → 10.3 years. Inflation at 6% → your money's value halves in 12 years. This shortcut works for rates between 6–20% with less than 1% error. Use it to compare any investment or evaluate how inflation erodes wealth.
💹 Compound Interest Calculator
📅 Year-wise Breakdown
| Year | Opening Balance | Interest Earned | Closing Balance | Growth |
|---|---|---|---|---|
| 1 | ₹1,00,000 | ₹10,381 | ₹1,10,381 | |
| 2 | ₹1,10,381 | ₹11,459 | ₹1,21,840 | |
| 3 | ₹1,21,840 | ₹12,649 | ₹1,34,489 | |
| 4 | ₹1,34,489 | ₹13,962 | ₹1,48,451 | |
| 5 | ₹1,48,451 | ₹15,411 | ₹1,63,862 |
How to Use This Compound Interest Calculator
Enter your Principal, Annual Interest Rate, Time Period, and select Compounding Frequency. Click Calculate to instantly see maturity value, year-wise growth table, and interactive chart — no login required. Switch tabs for contributions, goal planning, and frequency comparison.
Compound Interest Formula Explained
A = P × (1 + r/n)nt — where P = Principal, r = rate (decimal), n = compounding freq/year, t = years. Example: ₹1,00,000 at 10% quarterly for 5 years: A = 1,00,000 × (1.025)20 = ₹1,63,862. Simple interest gives only ₹1,50,000 — CI gives ₹13,862 more!
Real-Life Compound Interest Examples India 2025
🏦 SBI FD (7.1%): ₹10L for 5 years → ₹14.13L maturity (quarterly compounding). 📮 PPF (7.1%): ₹1.5L/year for 15 years → ₹40.68L (tax-free). 📈 Nifty 50 SIP: ₹5,000/month at 12% for 20 years → ₹49.96L (invested ₹12L). 🎓 Child Education: ₹2L today at 12% for 18 years → ₹19.46L for college.
Compound Interest vs Simple Interest
For ₹5,00,000 at 8% for 10 years — Simple Interest: ₹9,00,000. Compound Interest (Quarterly): ₹11,10,537 — ₹2,10,537 more! The power of compounding grows exponentially. At 20 years, the difference triples. Start investing early — even 5 extra years can add lakhs to your corpus.
Frequently Asked Questions
How accurate is Rule of 72 for Indian investments?
For rates 6–20%, Rule of 72 is accurate within 1–3%. Exact calculations: At 6%: Rule of 72 says 12 years, exact = 11.9 years (error: 0.8%). At 10%: Rule says 7.2 years, exact = 7.27 years (1% error). At 15%: Rule says 4.8 years, exact = 4.96 years (3% error). At 1% (savings account): Rule says 72 years, exact = 69.7 years (3% error). For mental math and quick comparisons, Rule of 72 is reliable enough for all practical decisions.
What variations of Rule of 72 exist?
Rule of 72 variants: Rule of 69.3 (more accurate for continuous compounding). Rule of 70 (used for inflation/GDP doubling — easier mental math). Rule of 115 (for tripling money — 115 ÷ rate). Rule of 144 (for 4× money — 144 ÷ rate). Applications: 6% inflation → money value halves in 72÷6=12 years. 7% GDP growth → economy doubles in 72÷7≈10 years. 36% credit card rate → debt doubles in 72÷36=2 years.
How can I use Rule of 72 to compare Indian investment options?
Quick comparison matrix: Savings account (3.5%) → doubles in 20.6 years. FD (7%) → 10.3 years. PPF (7.1%) → 10.1 years. NPS (10% avg) → 7.2 years. Nifty 50 (12% CAGR) → 6 years. Mid Cap MF (14%) → 5.1 years. Real estate (8%) → 9 years. Gold (8% CAGR) → 9 years. Key insight: equity MF doubles money 2× faster than FD. Over 30 years: equity doubles 5–6 times vs FD's 3 times — 8× vs 3× multiplication.
What does Rule of 72 tell us about inflation?
Inflation uses Rule of 72 in reverse — it tells you how fast your money loses value. At 6% inflation: purchasing power halves in 12 years. A ₹10,000 monthly expense today needs ₹20,000 in 12 years. ₹1Cr retirement corpus at 60 → real value ₹50L by 72. This is why financial planners say "you need ₹3–5Cr for retirement" even if ₹1Cr feels like a lot today. Inflation-beating returns are non-negotiable for real wealth creation.