Simple Interest Calculator — Quick Interest Calculations
Calculate simple interest for any principal amount rate and time period. Understand the difference between simple and compound interest with examples.
Simple interest is the most basic form of interest calculation where interest is charged only on the original principal amount and not on accumulated interest. While most modern financial products use compound interest simple interest is still used in some short-term loans personal lending between individuals and certain government savings schemes. Understanding simple interest helps you appreciate why compound interest is more powerful and how even small differences in calculation method can lead to large differences over time.
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Key Information
| Parameter | Details |
|---|---|
| SI Formula | Simple Interest = P x R x T / 100 |
| Used In | Short-term loans and some govt schemes |
| Difference from CI | CI earns interest on interest SI does not |
| Key Variables | P = Principal, R = Rate, T = Time |
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Use Calculator NowFrequently Asked Questions
How is simple interest calculated?
Simple Interest = Principal x Rate x Time / 100. For example if you invest Rs 1 lakh at 8% for 3 years the simple interest = 100000 x 8 x 3 / 100 = Rs 24000. Your total amount would be Rs 1.24 lakh. Compare this with compound interest where the same investment would grow to Rs 1.26 lakh due to interest-on-interest.
When is simple interest used in real life?
Simple interest is used in some short-term personal loans between friends or family in certain government bonds and treasury bills in car loans from some lenders and in calculating interest for partial periods. Most bank FDs savings accounts and long-term loans use compound interest which gives higher returns to investors and higher cost to borrowers.
Simple vs compound interest which earns more?
Compound interest always earns more than simple interest given the same rate and time period. The difference grows dramatically over longer periods. Rs 1 lakh at 10% for 10 years: SI gives Rs 2 lakh total while CI gives Rs 2.59 lakh. For 20 years: SI gives Rs 3 lakh while CI gives Rs 6.73 lakh. This is why long-term investors prefer compound interest instruments.
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Last updated: 24 March 2026