Compound Interest Calculator
Calculate compound vs simple interest with growth chart
Total Invested
₹1.00 L
Interest Earned
₹2.30 L
Total Value
₹3.30 L
📈 Compound vs Simple Interest
Compound interest earns ₹1.10 L more than simple interest over 10 years
⚡ Rule of 72
6.0 yrs
to double at 12%
🎯 Growth Multiplier
3.3x
in 10 years
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📖 Learn More About Compound Interest Calculator
How Compound Interest Works — The 8th Wonder of the World
Compound interest is often called the "8th wonder of the world" — a phrase attributed to Albert Einstein. Unlike simple interest (which calculates interest only on the original principal), compound interest calculates interest on both the principal AND on all previously accumulated interest. This creates an exponential growth curve that accelerates over time, making early investment extraordinarily powerful.
The mechanics are simple but the effects are profound. In year 1, you earn interest on your principal. In year 2, you earn interest on (principal + year 1 interest). In year 3, you earn on (principal + year 1 + year 2 interest) — and so on. This snowball effect means the absolute amount of interest earned each year keeps increasing even if the rate stays constant. A ₹1,00,000 investment at 12% earns ₹12,000 in year 1 but ₹37,645 in year 10 (on the same rate) — just from compounding.
Compounding frequency matters too. The more often interest is compounded (daily vs monthly vs quarterly vs annually), the higher your final corpus — because each period's interest starts earning its own interest sooner. Indian FDs typically compound quarterly; savings accounts often daily. Equity mutual funds effectively compound continuously as NAV grows each day. The mathematical formula captures all these variations neatly.
The most critical insight about compound interest is the non-linearity of time. The first 10 years of compounding might grow ₹1L to ₹3.1L. The next 10 years grow it to ₹9.6L. The 10 years after that (years 20-30) grow it to ₹29.9L. Each decade produces more wealth than all previous decades combined. This is why starting early and staying invested long-term is the cornerstone of all wealth-building advice.
📐 Compound Interest Formula
A = P × (1 + r/n)^(n×t)
With monthly additions: A = P(1+r/n)^(nt) + M × [(1+r/n)^(nt) - 1] / (r/n)
A = Final Amount (maturity value)
P = Principal (initial investment)
r = Annual interest rate (decimal)
n = Compounding frequency per year (Daily=365, Monthly=12, Quarterly=4, Annual=1)
t = Time in years
M = Monthly addition amount
✏️ Worked Example
You invest ₹2,00,000 at 12% p.a. with monthly compounding for 10 years, adding ₹5,000/month:
Lump Sum: 2,00,000 × (1 + 0.12/12)^(12×10)
= 2,00,000 × (1.01)^120 = 2,00,000 × 3.3004
= ₹6,60,084 (from initial investment)
Monthly SIP: 5,000 × [(1.01^120 - 1) / 0.01]
= 5,000 × 230.04 = ₹11,50,193
Total = ₹18,10,277 from ₹8,00,000 invested
Total invested: ₹2L + (₹5K × 120 months) = ₹8,00,000 | Compound gain: ₹10,10,277
💡 Compound Interest Tips for Wealth Building
Start Yesterday, Start Today
Every year you delay costs exponentially. Delaying your ₹10,000/month SIP by just 5 years (starting at 30 vs 25) reduces your retirement corpus at 60 by ~₹1.5 Crore at 12% CAGR. The cost of waiting grows non-linearly — each additional year of delay costs more than the previous one.
Never Break Your Compounding Cycle
Redeeming investments early breaks compounding. If you redeem a ₹10L investment after 10 years (instead of 20), you miss the most powerful compounding years (years 10-20 typically produce more wealth than years 1-10). Stay invested through market volatility.
Rate Matters More Than You Think
At ₹10,000/month for 20 years: at 8% = ₹58.9L. At 12% = ₹91.9L. At 15% = ₹1.51 Crore. Moving from 8% to 12% (50% rate increase) produces 56% more wealth. Higher rates are extremely powerful over long horizons — pursue them with appropriate risk tolerance.
Reinvest All Returns (Growth Option)
Always choose the Growth option (not Dividend) in mutual funds. Dividends break compounding — you receive cash and lose the compounding benefit of that amount. Growth option reinvests everything automatically. Over 20 years, growth option can be 40-60% more valuable than dividend option.
Use Step-Up SIP for Accelerated Growth
Increase your SIP amount by 10-15% each year (Step-Up SIP). If your salary grows, your SIP should too. A ₹10,000/month SIP stepped up 10% annually for 20 years (at 12% CAGR) produces ₹2.5 Crore vs ₹91.9L without step-up — nearly 3x more corpus from the same habit.
Tax-Efficient Compounding
Compounding in tax-inefficient accounts leaks wealth. FD interest taxed at 30% effectively compounds at only 70% of the rate. PPF (7.1% tax-free) > FD (8% pre-tax at 30% slab = 5.6% post-tax). ELSS mutual funds compound tax-free during the holding period, with only 12.5% LTCG on exit gains above ₹1.25L.
Avoid Compound Interest on Debt
Compound interest works against you in credit card debt (36-42% p.a. compounded monthly). ₹50,000 credit card debt unpaid for 3 years becomes ₹1,47,000+ at 36%! Always pay credit cards in full. The same mathematics that builds wealth can destroy it when you're on the borrower's side.
The Power of Compounding — ₹1,00,000 Over Time
| Years | 6% (FD/Savings) | 8% (Debt MF) | 12% (Equity MF) | 15% (Aggressive) |
|---|---|---|---|---|
| 5 years | ₹1.34L | ₹1.47L | ₹1.76L | ₹2.01L |
| 10 years | ₹1.79L | ₹2.16L | ₹3.11L | ₹4.05L |
| 15 years | ₹2.40L | ₹3.17L | ₹5.47L | ₹8.14L |
| 20 years | ₹3.21L | ₹4.66L | ₹9.65L | ₹16.37L |
| 25 years | ₹4.29L | ₹6.85L | ₹17.00L | ₹32.92L |
| 30 years | ₹5.74L | ₹10.06L | ₹29.96L | ₹66.21L |
All values assume annual compounding of ₹1,00,000 lump sum. Equity returns are illustrative — past performance doesn't guarantee future results.
Frequently Asked Questions
What is compound interest and how is it different from simple interest?
Compound interest is calculated on both the initial principal and the accumulated interest from previous periods — 'interest on interest.' Simple interest is calculated only on the principal. Example: ₹1,00,000 at 10% for 5 years — Simple Interest gives ₹1,50,000 (₹50,000 interest). Compound interest (annual) gives ₹1,61,051 (₹61,051 interest) — 22% more! The gap widens dramatically over longer periods.
What is the compound interest formula?
A = P × (1 + r/n)^(n×t), where: A = final maturity amount, P = principal (initial investment), r = annual interest rate in decimal (e.g., 12% = 0.12), n = number of times interest compounds per year (daily=365, monthly=12, quarterly=4, annually=1), t = time period in years. For monthly additions, the formula expands using the Future Value of Annuity formula.
What is the Rule of 72?
The Rule of 72 is a quick mental math shortcut: divide 72 by the annual interest rate to find how many years it takes to double your money. At 6% — doubles in 12 years. At 8% — doubles in 9 years. At 12% — doubles in 6 years. At 15% — doubles in 4.8 years. Similarly, Rule of 114 estimates how long to triple your money (114 ÷ rate), and Rule of 144 for quadrupling (144 ÷ rate).
How does compounding frequency affect my returns?
More frequent compounding always gives higher returns, but the incremental benefit diminishes: ₹1,00,000 at 10% for 10 years — Annually: ₹2,59,374. Quarterly: ₹2,68,506. Monthly: ₹2,70,704. Daily: ₹2,71,791. Moving from annual to quarterly compounding adds ₹9,132 (3.5% more). Monthly vs quarterly adds only ₹2,198 more. The biggest jump is from simple to compound (any frequency).
What investments use compound interest in India?
Compound interest is at work in: Fixed Deposits (quarterly compounding), PPF and PF (annual compounding), Recurring Deposits, Savings Account interest, Mutual Fund SIPs (growth option compounds as NAV grows), NPS (market-linked compounding), and all equity investments. Your equity SIP compounding at 12% CAGR for 30 years turns ₹10,000/month into ~₹3.5 Crore from just ₹36L invested.
How does the Power of Compounding work with SIP?
SIP (Systematic Investment Plan) harnesses compounding on two levels: (1) Your capital compounds as the investment grows in value, (2) Each new SIP installment also starts compounding from its investment date. A ₹10,000/month SIP in an equity fund returning 12% CAGR: After 10 years = ₹23.2L (from ₹12L invested). After 20 years = ₹91.9L (from ₹24L invested). After 30 years = ₹3.49 Crore (from ₹36L invested). The third decade generates more wealth than the first two combined!
What is the difference between CAGR and compound interest?
CAGR (Compound Annual Growth Rate) measures how much an investment grew per year on a compounded basis, looking backward. Compound Interest calculates future value given a fixed rate, looking forward. CAGR = (End Value / Start Value)^(1/years) − 1. Example: ₹1,00,000 grows to ₹2,59,374 in 10 years → CAGR = (2.59374)^(0.1) − 1 = 10%. They are two sides of the same mathematical coin.
How does inflation affect compound interest?
Inflation erodes the real value of your compounding returns. Real Return = Nominal Rate − Inflation Rate (approximately). If your FD earns 7% and inflation is 6%, your real return is only ~1%. This is why financial experts recommend beating inflation through equity investments (targeting 12-15% returns vs 6% inflation = 6-9% real returns). Always evaluate investments in real (inflation-adjusted) terms, not just nominal returns.
What is the effect of starting early on compound interest?
Starting early is the single most powerful factor in compounding. Consider this: Investor A invests ₹5,000/month from age 25-35 (10 years = ₹6L total) then stops. Investor B invests ₹5,000/month from age 35-60 (25 years = ₹15L total). At 12% CAGR, at age 60: Investor A has ~₹2.97 Crore. Investor B has ~₹94L. Investor A invested less than half but ends up with 3x more — purely due to 10 extra years of compounding!
How is compound interest calculated in Indian FDs?
Indian banks typically compound FD interest quarterly. The formula: A = P × (1 + r/4)^(4×t). For a 3-year FD of ₹5L at 7.25%: A = 5,00,000 × (1 + 0.0725/4)^12 = 5,00,000 × (1.018125)^12 = 5,00,000 × 1.24131 = ₹6,20,655. TDS at 10% applies on interest exceeding ₹40,000/year (₹50,000 for senior citizens).