Finance & Money
Simple Interest Calculator
Use this simple interest calculator when interest does not compound and you need the interest amount or final balance.
Interest earned
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- Final balance
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Student quick launch
Grade planning, algebra checks, and formulas students reach for most.
Study path
Use this calculator with
Follow these when you want the formula behind the answer, a short lesson, or nearby tools in the same topic.
What the simple interest calculator solves
Use this simple interest calculator when interest does not compound and you need the interest amount or final balance.
Formula
How to use it
- Enter principal.
- Enter annual rate.
- Enter time in years.
How to read the answer
Simple interest grows linearly because interest is calculated only on the original principal.
Common mistakes and edge cases
- Convert percent rate to a decimal in hand calculations.
- Use years for time unless you convert months or days.
- Simple interest is not the same as compound interest.
Worked examples
Three-year simple interest
Interest earned
$150.00
Short-term loan
Interest earned
$100.00
Frequently asked questions
Does simple interest compound?+
No. Interest is calculated only on the original principal.
When is simple interest used?+
It appears in some short-term loans, notes, and classroom finance problems.
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Last updated: May 8, 2026