Simple Interest Calculator
SI = P × R × T ÷ 100 — flat-rate interest on principal only.
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About this calculator
Simple interest grows linearly — it is always calculated on the original principal, never on previously accumulated interest. Short-term borrowings, some vehicle finance and informal lending often use flat/simple interest.
Compare it with the Compound Interest calculator to see how powerful reinvesting interest can be over long tenures.
Formula
SI = (P × R × T) / 100
Frequently Asked Questions
When is simple interest used?
Commonly for short-term loans, hire purchase agreements and some gold/vehicle loans where interest is charged flat on the original amount.
Can time be in months?
Yes — enter years as a decimal, e.g. 18 months = 1.5.