How to use this calculator
- Enter or choose principal.
- Enter or choose interest rate (per year).
- Enter or choose time.
- Enter or choose time in.
- The simple interest updates as you type. Use Copy result or Share to keep it.
Formula
I = P × R × T ÷ 100
- I
- interest
- P
- principal
- R
- rate per year (%)
- T
- time in years (months ÷ 12, days ÷ 365)
Worked example
- P = ₹10,000, R = 5%, T = 3 years.
- I = 10,000 × 5 × 3 ÷ 100 = ₹1,500.
- Total = 10,000 + 1,500 = ₹11,500.
The interest is ₹1,500, giving ₹11,500 in total.
What the result means
Simple interest grows in a straight line: ₹500 every year in the example. Some short-term loans and fixed deposits paying out interest use it; most savings and loans compound.
Assumptions and limits
- A year is 365 days when time is entered in days.
- Interest is not added back to the principal.
- Banks may use 360-day or actual/actual day counts for some products.
Questions
How do I find the rate if I know the interest?
Rearrange the formula: R = I × 100 ÷ (P × T). For ₹1,500 interest on ₹10,000 over 3 years, R = 150,000 ÷ 30,000 = 5%.
When is simple interest used?
For some personal loans, car loans quoted at flat rates, short-term borrowing and deposits that pay interest out instead of reinvesting it.
Please note: This calculator gives estimates for planning. It is not financial advice, and lenders’ actual terms, fees and rounding may differ.