Simple Interest Calculator

Total amount = P + SI

A simple interest calculator computes interest earned or paid on a principal amount at a flat rate without compounding. Unlike compound interest, where you earn interest on interest, simple interest is always calculated on the original principal alone. It is used for short-term loans, some government schemes, and quick estimation.

The formula is straightforward: SI = (Principal × Rate × Time) / 100. For example, ₹1 lakh at 8% for 3 years earns ₹24,000 in simple interest — giving a total of ₹1.24 lakh. Our free simple interest calculator online computes this instantly and also shows the comparison with compound interest so you can appreciate the difference compounding makes.

Common use cases for simple interest in India include: post office schemes (some use SI), flat-rate car loans, short-term personal loans, and interest on late GST payments (calculated at 18% per annum simple interest). Use this tool for quick, accurate calculations without any complexity.