Compound interest calculator
Compound interest is interest on your interest. See how a sum grows over time, and how much more compounding gives you than simple interest.
Rules for FY 2026-27 · Checked 24 October 2026
2.59 lakh, of which ₹1.59L is interest.
- At 10% your money doubles every 7.3 years.
- Simple interest would give only ₹2L: compounding adds ₹59.4k.
- Money put in₹1,00,000
- Interest earned₹1,59,374
Year-by-year table
| Year | Put in | Interest | Value |
|---|---|---|---|
| 1 | ₹1,00,000 | ₹10,000 | ₹1,10,000 |
| 2 | ₹1,00,000 | ₹21,000 | ₹1,21,000 |
| 3 | ₹1,00,000 | ₹33,100 | ₹1,33,100 |
| 4 | ₹1,00,000 | ₹46,410 | ₹1,46,410 |
| 5 | ₹1,00,000 | ₹61,051 | ₹1,61,051 |
| 6 | ₹1,00,000 | ₹77,156 | ₹1,77,156 |
| 7 | ₹1,00,000 | ₹94,872 | ₹1,94,872 |
| 8 | ₹1,00,000 | ₹1,14,359 | ₹2,14,359 |
| 9 | ₹1,00,000 | ₹1,35,795 | ₹2,35,795 |
| 10 | ₹1,00,000 | ₹1,59,374 | ₹2,59,374 |
The compound interest formula
A = P × (1 + r ÷ n)^(n × t), where P is the starting amount, r the yearly rate as a decimal, n how many times a year interest is added and t the number of years.
₹1 lakh at 10% for 10 years, compounded yearly, grows to about ₹2,59,374. With simple interest it would be only ₹2 lakh.
The rule of 72
Divide 72 by the interest rate to estimate how many years it takes to double your money. At 8% that is about 9 years; at 12%, about 6. The calculator shows the exact figure.
Why frequency matters
The more often interest is added, the faster money grows, because each addition starts earning sooner. The difference is small at low rates and grows with the rate and the time.
Frequently asked questions
What is the difference between simple and compound interest?
Simple interest is paid only on the original amount. Compound interest is also paid on the interest already earned, so the balance grows faster every year.
Which investments use compound interest?
Fixed deposits, recurring deposits, PPF, EPF, Sukanya Samriddhi and the growth of mutual funds all compound. Loans compound against you.
Sources: Reserve Bank of India