Simple Interest Calculator
Calculate simple interest and total amount over a fixed period.
Up to 100 billion
0.1% to 100%
1 to 100 years
Calculates simple interest — interest on the original principal only — and the total you have at the end, for any rate and period.
Understanding the result
Total interest grows in a straight line: double the time, double the interest. Final amount is the principal plus that interest.
Simple interest applies to some short-term loans and deposits, and to informal lending. Most savings, deposits and investments compound instead, which earns more over time.
How to use it
Enter the principal (in any currency), the annual interest rate in percent, and the time period in years or months.
How it works
A period in months is converted to years (18 months is 1.5 years). Interest and the final amount are rounded to whole numbers.
Interest = P × R × T ÷ 100
P = principal, R = annual rate %, T = years
Examples
100,000 for 10 years at 10%
Simple interest comes to 100,000, a final amount of 200,000. Compounded yearly at the same rate, the interest would be 159,374.
9 months at 8%
On 50,000, 9 months is 0.75 years: 50,000 × 8 × 0.75 ÷ 100 = 3,000.
See also
- Compound Interest Calculator — when interest is added to the principal and earns interest too.