Compound Interest Calculator
Choose principal, rate, time and compounding frequency — the final amount and total compound interest appear instantly.
How to use — Compound Interest Calculator
- Enter the principal amount — the money on which interest applies.
- Enter the annual interest rate and time (years).
- Choose the compounding frequency — banks usually compound quarterly.
- Click Calculate — see the total amount and compound interest.
FAQ
What is the compound interest formula?
A = P × (1 + r/n)^(n×t), where P = principal, r = annual rate (decimal), n = compounding frequency per year, t = years. Compound interest = A − P.
What's the difference between simple and compound interest?
Simple interest applies only to the principal. With compound interest, each period's interest gets added to the principal, and earns interest itself in the next period — so compound interest is much larger over the long term.
How much does compounding frequency matter?
The higher the frequency, the higher the return. ₹1 lakh @ 8% × 10 years: yearly = ₹2.16L, quarterly = ₹2.21L, monthly = ₹2.22L. The difference looks small but is significant on large amounts.
What is the Rule of 72?
The approximate time for money to double = 72 ÷ interest rate. E.g. at 8%, money doubles in ~9 years.