Simple Interest Calculator
Calculate simple interest and ending amount from principal, annual rate, and time.
Simple interest grows linearly over time, using principal x rate x time.
$900.00
$5,900.00
About the simple interest calculator
How this calculator works
Simple interest is the most direct finance formula in the set because the growth depends only on principal, annual rate, and time.
That makes the page useful for quick classroom checks, basic agreements, and side-by-side comparisons before moving to compound growth models.
Where it is useful
It is a good fit for educational examples and straightforward contracts where interest is not periodically added back into the balance.
Showing interest earned and ending amount together keeps the result practical instead of leaving users with only a raw formula output.
- Check a basic interest agreement without using a spreadsheet.
- Compare simple-interest growth with compound-interest growth.
- Work through finance homework or training examples quickly.
Example calculations
3 examples$5,000 at 6% for 3 years
$900 interest
$1,200 at 4% for 2 years
$96 interest
$10,000 at 5% for 1.5 years
$750 interest
Common uses
3 ideas- Check a basic interest agreement without using a spreadsheet.
- Compare simple-interest growth with compound-interest growth.
- Work through finance homework or training examples quickly.
FAQ
3 answersWhat is simple interest?
Simple interest uses principal x rate x time, so the interest grows linearly instead of compounding on previous interest.
Can I use partial years in the simple interest calculator?
Yes. Time can be entered as fractional years, which is useful when the investment or borrowing period is not a whole number.
How is simple interest different from compound interest?
Compound interest reinvests growth and earns interest on earlier interest, while simple interest only uses the starting principal.