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Calculators / Finance / Simple interest
Simple interest calculator
Calculate interest without compounding.
On this page
Interest1,500
Final balance11,500
Calculator controls
How to calculate
Calculate interest without compounding.
Interest = principal × annual rate ÷ 100 × years
Worked example
Principal: 10000; Annual rate (%): 5; Years: 3.
Interest: 1,500 ; Final balance: 11,500 .
Assumptions and limits
No compounding, additional deposits, tax, or fees.
Results are rounded for display; calculations use unrounded values. Read our calculation methodology.
Understanding the result
Simple interest is calculated only on the original principal. Interest does not itself earn additional interest in this model.
When this tool is useful
Check a straightforward interest agreement with a fixed principal and rate.
Understanding your inputs
| Input | What to enter |
|---|---|
| Principal | Enter a number of at least 0 and no more than 1000000000000. |
| Annual rate (%) | Enter a number of at least 0 and no more than 100. |
| Years | Enter a number of at least 0 and no more than 100. |
Frequently asked questions
How do I enter six months?
Enter 0.5 years when the rate is annual. Keep the rate and time basis consistent.
Why is this lower than compound interest?
Compounding adds earlier interest to the balance used in later periods. Simple interest always uses the original principal.