💹 Compound Interest Calculator

🔒 No signup, no login — free to use. This tool runs entirely in your browser; your numbers and files never leave your device.

See how your money grows when interest earns interest too.

What Is Compound Interest?

Compound interest means you earn interest not only on your original money, but also on the interest you have already earned. In simple interest, Rs 100,000 at 10% earns Rs 10,000 every year. In compound interest, the second year earns interest on Rs 110,000, so it earns Rs 11,000. The difference looks small at first, but over 10 or 20 years it becomes very large.

The formula is A = P × (1 + r/n)^(n×t), where P is principal, r is yearly rate, n is how many times interest is added per year, and t is years. More frequent compounding gives a slightly higher result. Monthly compounding beats yearly compounding, even at the same rate.

Compound interest is the reason starting early matters so much for savings and retirement. A person who starts saving at 25 ends up with much more than a person who starts at 35, even if the second person saves more each month. Use this calculator to test your own savings plan and see the difference time makes.

Read the full guide: How to Calculate Compound Interest  |  ← Back to all tools