Compound Interest Calculator
Calculate compound interest with monthly, quarterly, half-yearly, or yearly compounding. See how your money grows over time.
Compound Interest Calculator
Compound Interest Breakdown
Rule of 72 — Quick Reference
| Interest Rate | Money Doubles In |
|---|---|
| 6% | 12 years |
| 8% | 9 years |
| 10% | 7.2 years |
| 12% | 6 years |
| 15% | 4.8 years |
What is Compound Interest?
Compound interest is the eighth wonder of the world, as Albert Einstein allegedly remarked. It is the interest calculated on the initial principal and also on the accumulated interest of previous periods. Unlike simple interest, which is calculated only on the original principal, compound interest allows your money to grow exponentially over time because you earn interest on your interest.
In India, compound interest is the standard method used by banks for Fixed Deposits (FDs), Recurring Deposits (RDs), and most savings instruments. Understanding compound interest is essential for making informed decisions about investments, loans, and long-term financial planning.
Compound Interest Formula
The compound interest formula is:
A = P(1 + r/n)^(nt)
Where:
- A = Final amount (principal + interest)
- P = Principal amount (initial investment)
- r = Annual interest rate (in decimal, e.g., 8% = 0.08)
- n = Number of times interest is compounded per year
- t = Time period in years
Compound Interest (CI) = A − P
How to Use This Compound Interest Calculator
- Enter the principal amount — The initial amount you are investing or the loan amount.
- Enter the annual interest rate — The yearly interest rate offered by your bank or financial institution.
- Select compounding frequency — Choose how often interest is compounded: monthly, quarterly, half-yearly, or yearly.
- Enter the time period — The number of years you plan to keep the investment or the loan tenure.
- Click Calculate — View the compound interest, total amount, and effective annual rate.
Compound Interest vs Simple Interest
| Feature | Compound Interest (CI) | Simple Interest (SI) |
|---|---|---|
| Formula | A = P(1 + r/n)^(nt) | SI = P × R × T / 100 |
| Interest on interest | Yes | No |
| Growth pattern | Exponential | Linear |
| ₹1L at 10% for 10 years | ₹2,59,374 | ₹2,00,000 |
| Best for | Long-term investments | Short-term loans |
| Used in | FDs, RDs, mutual funds | Some car loans, short-term deposits |
Real-World Examples of Compound Interest
Fixed Deposits (FDs): Most banks in India compound interest quarterly on FDs. If you deposit ₹5,00,000 at 7% for 5 years with quarterly compounding, you will receive approximately ₹7,07,389 — earning ₹2,07,389 in compound interest.
Education Loans: Education loans typically use compound interest. A loan of ₹10,00,000 at 9% for 10 years with monthly compounding results in a total repayment of approximately ₹24,51,357 — meaning you pay ₹14,51,357 in interest alone.
Recurring Deposits (RDs): RDs use compound interest with quarterly compounding. If you deposit ₹10,000 per month for 5 years at 6.5%, your maturity amount will be approximately ₹7,11,736, earning interest of ₹1,11,736 on your total deposit of ₹6,00,000.
Home Loans: Home loans in India use monthly compounding. On a ₹50,00,000 loan at 8.5% for 20 years, the total interest paid is approximately ₹54,13,794 — more than the principal itself. This is why even a small difference in interest rate can save lakhs over the loan tenure.
Tips to Maximize Compound Interest
- Start early: The earlier you start investing, the more time compound interest has to work. A 25-year-old investing ₹5,000/month at 12% will have ₹1.76 crore at 60, while a 35-year-old will have only ₹47 lakh.
- Increase frequency: Monthly compounding yields more than yearly compounding at the same rate.
- Reinvest returns: Always reinvest dividends and interest to benefit from compounding.
- Avoid withdrawals: Withdrawing interest breaks the compounding cycle and reduces long-term returns.
- Negotiate rates: Even a 0.5% higher rate can make a significant difference over long periods.