Simple Interest Calculator
Interest and total on a principal using simple interest: I = P × R × T ÷ 100.
Best for: Use it for short-term loans, car-title or some personal loans quoted at simple interest, or to compare against a compound-interest product.
Purpose: Interest and total on a principal using simple interest: I = P × R × T ÷ 100.
Input
Result
EstimateTotal amount
$1,150
What to do next
Next: SSI Payment CalculatorMore about this result
- Type
- Industry Standard
- Method
- Industry-standard method
- Confidence
- High
Uses the standard formula and conventions the industry relies on.
Explore scenarios
- Time· Most impactful— +2 yrs
- Interest rate· Least impactful— +2%
The interest grows in a straight line with time. Simple interest is common for short-term loans and some bonds; for savings and most loans, compound interest applies and grows faster.
- Inflation often matters more than expected over the long run.
- Small rate changes can significantly affect total outcomes.
- Long-term consistency usually beats short-term timing.
Small, consistent changes compound: time in the market usually beats timing the market.
How it's calculated & sources
Free & no sign-up · runs entirely in your browser. Results are estimates for general information, not professional advice — verify important decisions with a qualified expert. Last reviewed June 2026.
How it works
Interest = P × R × T ÷ 100 and Total = P + Interest. Interest is charged on the original principal only — it does not compound.
Example
$1,000 at 5% simple interest for 3 years = 1000 × 5 × 3 ÷ 100 = $150 interest, total $1,150.
Frequently asked questions
How is simple interest different from compound interest?+
Simple interest is always charged on the original principal, so it grows in a straight line. Compound interest adds earned interest back to the balance, so it grows faster over time.
Can I use months instead of years?+
Yes — switch the time unit to months and the calculator converts it to years (months ÷ 12) before applying the formula.
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