Calculate Simple Interest instantly using the SI = P × R × T / 100 formula
Enter the original loan amount or investment amount (P). This is the base amount on which interest will be calculated.
Enter the annual interest rate (R) as a percentage. For example, a bank offering 8% per annum on a fixed deposit.
Enter the duration in Years, Months, or Days. The calculator automatically converts months and days to years for accurate calculation.
The calculator shows Simple Interest, Total Amount (Principal + SI), and the effective return percentage — all instantly.
Simple Interest Formula: SI = (P × R × T) / 100
Total Amount: A = P + SI = P × (1 + R×T/100)
Example: P=₹1,00,000 @ R=8% for T=3 years → SI = ₹24,000 → Total = ₹1,24,000
Simple Interest (SI) is calculated only on the original principal amount, not on accumulated interest. In India, it is commonly used in short-term personal loans, vehicle loans, some government savings schemes like NSC, and short-duration fixed deposits.
Simple Interest = (Principal × Rate × Time) / 100. For example, on ₹1,00,000 at 8% for 3 years: SI = (1,00,000 × 8 × 3) / 100 = ₹24,000. Total Amount = Principal + SI = ₹1,24,000.
Simple Interest is calculated only on the principal. Compound Interest is calculated on principal plus previously earned interest — so interest earns interest. For the same rate and time, Compound Interest always gives more returns than Simple Interest for investments, and costs more for loans.
For months: convert to years by dividing by 12. For days: divide by 365. Example: SI for 6 months at 10% on ₹50,000 = (50,000 × 10 × 0.5) / 100 = ₹2,500. Our calculator does this conversion automatically.
For investors, Compound Interest is always better because your returns also earn returns over time. For borrowers, Simple Interest loans are cheaper. Most mutual funds, PPF, and FDs in India use compound interest, making them more wealth-building than simple interest instruments.