Interest Amount
0.00
Total Amount
0.00
Simple Interest Formula
I = P × r × t
Where:
I = Interest
P = Principal
r = Rate of Interest (in decimal)
t = Time Period (in years)
About the Interest Calculator
This calculator works out both simple and compound interest on a principal amount over time. Simple interest is charged only on the original principal; compound interest is charged on the principal plus previously accrued interest — which grows much faster.
Enter your principal, rate and duration and it computes the interest and final amount in your browser. It's handy for comparing savings, fixed deposits, or the true cost of borrowing.
How to use the Interest Calculator
- 1Enter the principal amount.
- 2Enter the annual interest rate and the time period.
- 3Choose simple or compound (and, for compound, the compounding frequency).
- 4Read off the interest earned and the final total.
Common uses
Comparing savings/FDs
See how much a deposit grows at a given rate and term.
Understanding loan cost
Estimate the interest you'll pay on borrowed money.
Financial planning
Project the future value of an investment.
Frequently asked questions
What's the difference between simple and compound interest?
Simple interest is calculated only on the principal. Compound interest is calculated on the principal plus accumulated interest, so it grows faster over time.
How does compounding frequency matter?
More frequent compounding (monthly vs yearly) yields slightly more interest, because interest starts earning interest sooner.
Is this financial advice?
No — it's a math tool. It shows the arithmetic; it doesn't account for taxes, fees, or changing rates.
Are my figures sent anywhere?
No. The calculation runs entirely in your browser.