How to use Simple Interest Calculator
Simple interest does not add interest to the principal for future calculations. Equal time periods therefore produce equal interest at the same rate. It is useful for checking a basic contract or classroom calculation.
Use the same time basis as the annual rate. Six months is 0.5 years in this tool. For a contract using actual days, verify its year-length convention before translating days into years.
The formula
Interest = principal × annual rate / 100 × years
Total amount = principal + interest
A worked example
Principal (₹): 10000 · Annual rate (%): 5 · Duration (years): 2
Simple interest: ₹1,000.00
Questions about this calculation
How do I enter six months?
Enter 0.5 years.
Is this the same as EMI interest?
No. A reducing-balance loan changes the outstanding principal after each payment. Use the EMI calculator for that model.
Formula checks: 2026-10-08. Assumptions & corrections.