Compound Interest Calculator
Calculate how your investment grows with compound interest, including total interest earned and optional periodic contributions.
Swipe to choose a compounding frequencyChoose a compounding frequency
Enter the initial principal, annual interest rate, duration, and an optional contribution for each compounding period.
Initial principal
Annual interest rate
Duration
Contribution per period (optional)
How is compound interest calculated?
Compound interest grows an investment faster than simple interest because interest is earned on both the principal and the interest already accumulated.
Here, A is the final amount, P is the principal, r is the annual interest rate, n is the number of times interest compounds per year, and t is the duration in years. C is the contribution made at the end of each compounding period. If you add a regular contribution each period, it is added on top of this growth.
Compound interest example
Suppose you invest 100,000 at an annual interest rate of 8%, compounded monthly, for 10 years, with no extra contributions.
The investment compounds 12 times a year for 10 years, which is 120 total periods.
Final amount: about 221,964.02, including about 121,964.02 in interest.
What affects your final amount?
Interest rate
A higher annual interest rate compounds into significantly more growth over longer durations.
Compounding frequency
Compounding more often, such as monthly or daily instead of annually, slightly increases the final amount for the same nominal rate.
Duration
Compound interest benefits strongly from time. Longer durations allow interest to compound on itself many more times.
Regular contributions
Adding a fixed amount every compounding period, such as a monthly deposit, can substantially increase the final amount compared to a one-time investment alone.
FAQ
Frequently asked questions
What is compound interest?
Compound interest is interest calculated on both the original principal and the interest already earned.
How does compounding frequency affect growth?
More frequent compounding generally produces slightly more growth because interest is added to the balance more often.
What does the optional contribution field do?
It adds a fixed amount at the end of each compounding period. If monthly compounding is selected, the contribution is added monthly.
Is this the same as an EMI or loan calculator?
No. This calculator estimates investment or deposit growth. Use the Loan Calculator or EMI Calculator for loan repayments.