Simple Interest Calculator
Calculate simple interest earned or paid on a principal amount. Simple interest is calculated only on the original principal.
Total Amount
How to use the Simple Interest Calculator
- Enter the principal amount.
- Enter the annual interest rate.
- Enter the time in years and, if needed, extra months.
- Click Calculate to see the simple interest and the total amount.
Formula used
Worked example
₹1,00,000 at 8% for 3 years
SI = 1,00,000 × 8 × 3 ÷ 100 = ₹24,000
Total amount = ₹1,24,000
Where simple interest is used
Simple interest is common for short-term personal loans between people, some gold loans, car loans quoted at a "flat rate", and in school maths. Most bank deposits and home loans use compound or reducing-balance interest instead, which is why the same rate can give different results.
Tips for accurate results
- Convert months to years by dividing by 12 (6 months = 0.5 years).
- To find the rate: R = SI × 100 ÷ (P × T).
- To find the time: T = SI × 100 ÷ (P × R).
Frequently Asked Questions
For the same rate, simple interest costs less than compound interest. But compare the effective annual rate, not just the headline number.
Use T = days ÷ 365.
A flat rate charges simple interest on the full original loan for the whole tenure, so it is more expensive than the same reducing-balance rate.
Content reviewed by Vinod, Easy Smart Calculator · Last updated October 2026
How Simple Interest Works
Simple interest is calculated using the formula SI = P × R × T, where P is principal, R is annual interest rate, and T is time in years. The interest amount stays the same each period because it's calculated only on the original principal.
Total Amount = P + SI
Example
₹50,000 at 6% for 3 years:
SI = 50000 × 6 × 3 / 100 = ₹9,000
Total = ₹59,000