๐Ÿ”
Home โ€บ Calculators โ€บ Compound Interest Calculator
๐Ÿ“‰

Compound Interest Calculator

Calculate compound interest on your investment

๐Ÿ‡ฎ๐Ÿ‡ณ Indian Rupee (โ‚น)
Principal Amount
โ‚น
Annual Rate 10%
% p.a.
Time Period 5 Yrs
Years
Compounding Frequency
Total Amount
-
-
Principal
-
Compound Interest

What is Compound Interest?

Compound interest is interest earned on both the principal amount and the interest that has already been accumulated. In contrast, simple interest is calculated only on the original principal. This difference seems small initially but becomes enormous over long time periods โ€” which is why Albert Einstein reportedly called compound interest the eighth wonder of the world (though thats probably a myth, the point still stands).

Every long-term investor, whether in FDs, PPF, mutual funds, or stocks, benefits from compounding. The longer you stay invested, the more powerful it becomes. This is the fundamental reason why starting early is so important in personal finance.

Compound Interest Formula

A = P ร— (1 + r/n)^(nร—t) Where: A = Final amount (maturity value) P = Principal (initial investment) r = Annual interest rate (as decimal, so 8% = 0.08) n = Number of times interest compounds per year (1 = annually, 4 = quarterly, 12 = monthly, 365 = daily) t = Time in years Compound Interest = A - P

Example: โ‚น1 lakh invested at 10% per annum for 10 years:

Annual compounding: A = 1,00,000 ร— (1.10)^10 = โ‚น2,59,374

Monthly compounding: A = 1,00,000 ร— (1 + 0.10/12)^(12ร—10) = โ‚น2,70,704

More frequent compounding = more interest. The difference compounds over time.

Simple Interest vs Compound Interest โ€” A Real Comparison

Let us say you invest โ‚น5 lakh at 8% for 20 years:

Simple Interest: Interest = 5,00,000 ร— 0.08 ร— 20 = โ‚น8,00,000. Total = โ‚น13,00,000

Compound Interest (annually): A = 5,00,000 ร— (1.08)^20 = โ‚น23,30,478

Difference: โ‚น10,30,478. Almost double. Same money, same rate, same time โ€” but compounding earned an extra โ‚น10 lakh.

Where Does Compound Interest Actually Apply?

Compound interest works in your favour when you invest: FDs (quarterly compounding), PPF (annual compounding), savings accounts (quarterly compounding), and equity mutual funds where reinvested gains generate further gains.

Compound interest works against you when you borrow and dont repay: credit card outstanding balance (daily compounding โ€” extremely dangerous), unpaid loans where interest keeps accumulating, and penal interest on overdue EMIs.

This is why credit card debt is so brutal โ€” at 36โ€“42% annual interest compounded daily, โ‚น50,000 unpaid for 2 years becomes over โ‚น1 lakh. Pay off credit card dues in full every month without exception.

FAQs

How does compounding frequency affect returns?
More frequent compounding gives higher effective returns, but the difference becomes smaller as frequency increases. Going from annual to quarterly compounding gives a meaningful boost. Going from monthly to daily compounding gives only a marginal difference. For practical purposes, quarterly compounding (most FDs) vs annual compounding (PPF) is the most common comparison. The effective annual rate (EAR) factors in compounding frequency for fair comparison.
What is the doubling time with compound interest?
Use the Rule of 72 โ€” divide 72 by the annual interest rate. At 8%, money doubles in 9 years. At 12%, in 6 years. At 6%, in 12 years. If you have 30 years of investing time at 12% returns, your money doubles approximately 5 times โ€” so โ‚น1 lakh becomes โ‚น32 lakh. This is the power of compounding over long periods.
Do mutual funds use compound interest?
Not exactly in the same formula sense, but the concept of compounding absolutely applies. When your mutual fund gains are reinvested (in growth option funds), those gains also generate further returns. In a dividend option, you receive payouts regularly and the base doesnt grow as fast. For long term wealth creation, always choose growth option so that compounding works fully in your favour.