Compound vs simple interest
Simple interest is paid only on the original amount. Compound interest is also paid on the interest already earned, so growth speeds up over time. ₹1 lakh at 10% for 20 years becomes ₹3 lakh with simple interest but ₹6.73 lakh with yearly compounding.
Related: Simple interest · FD calculator · SIP calculator · Inflation calculator
How to use the Compound Interest Calculator tool
- Enter the starting amount, the yearly rate and the number of years.
- Choose how often interest is compounded, and optionally a monthly addition.
- See the maturity amount, the interest earned and a year-by-year table.
Why SaralKit?
- Free forever: no "credits", no trial, no premium tier, no watermark and no daily limit.
- No account, ever: nothing to sign up for. Just open the page and use it.
- No data stored: your files and the numbers you type are processed by your own browser. We never upload, store or see them.
- Works offline: once the page has loaded, most tools keep working without internet.
- Open source: anyone can read the code on GitHub.
Frequently asked questions
What is the compound interest formula?
A = P × (1 + r/n)n×t, where P is the principal, r the yearly rate, n the number of times interest is added per year and t the number of years. Compound interest = A − P.
What is ₹1 lakh at 10% for 5 years with yearly compounding?
₹1,61,051, so the interest is ₹61,051. With simple interest it would be only ₹50,000.
Does compounding frequency matter?
Yes, a little. At 12% a year, monthly compounding gives an effective 12.68% a year, quarterly 12.55% and yearly 12%. Indian bank FDs usually compound quarterly.
Can I add money every month?
Yes. Use "Monthly addition" to see how regular top-ups grow along with the starting amount.