Compound Interest Calculator

What is compound interest?

Compound interest is interest earned on both the principal and on interest already earned. Over time, this “interest on interest” accelerates growth. The calculator above lets you choose yearly, half-yearly, quarterly, or monthly compounding. Banks in India typically compound FD interest quarterly; for the same nominal annual rate, more frequent compounding gives a slightly higher effective return, so comparing products by compounding frequency helps you get the best outcome.

In India, fixed deposits (FDs) and many savings products use quarterly compounding. The nominal rate (e.g. 7% p.a.) is applied every quarter, so the effective annual return is slightly higher. Use this calculator to see how much you will get at maturity for a given principal, rate, and tenure, and to compare different compounding frequencies before you invest.

Formula

The future value of a lump sum with compound interest depends on the principal, the annual rate, the number of years, and how many times per year interest is compounded. The formula is:

• P = Principal (initial amount)
• r = Annual interest rate as a decimal (e.g. 0.08 for 8%)
• k = Compounding periods per year (1 = yearly, 2 = half-yearly, 4 = quarterly, 12 = monthly)
• n = Time in years

Total interest = FV − P. More frequent compounding (higher k) gives a slightly higher FV for the same r and n.

Example calculation

Suppose you invest ₹1,00,000 (₹1 lakh) at an annual rate of 8% for 5 years. With yearly compounding (k = 1), the future value is ₹1,00,000 × (1.08)⁵ ≈ ₹1.47 lakh; total interest ≈ ₹47,000. With quarterly compounding (k = 4), FV ≈ ₹1.49 lakh and interest ≈ ₹49,000—about ₹2,000 more than yearly compounding. This shows how compounding frequency affects the result. Most Indian FDs use quarterly compounding. Use the calculator above to try different principal amounts, rates, tenures, and compounding frequencies (yearly, half-yearly, quarterly, monthly) to plan your savings or compare products.

Benefits of Using This Calculator

A compound interest calculator shows how your money can grow with different compounding frequencies (yearly, half-yearly, quarterly, monthly), so you can compare products like FDs and mutual funds. It helps you see the effect of interest on interest over time and plan for long-term goals. Use it to set realistic expectations for savings and investments.

You can try different principals, rates, and tenures to see how small changes in rate or time can make a big difference to the final amount. Use it when planning FDs, comparing bank offers, or illustrating the power of compounding for long-term goals like retirement or education.

How to Use This Calculator

Enter the principal amount in rupees (the sum you are investing or depositing), the annual interest rate as a percentage (e.g. 7 or 8), and the time in years. Select the compounding frequency: yearly, half-yearly, quarterly, or monthly. For most Indian fixed deposits, choose quarterly. The calculator will show the future value and the total interest earned.

Change any input to compare scenarios—for example, the same principal at 7% vs 8%, or 5 years vs 10 years. The tool is useful for FDs, recurring deposits (for the maturity of each deposit), and any investment that compounds at a fixed rate. Remember that actual returns from market-linked products like mutual funds are not constant; use this for fixed-rate products or for rough illustrations.

FAQs