What this calculator shows you
- Interest Calculation
- Calculate interest earned or owed
- Flexible Inputs
- Any principal, rate, and time
- Total Amount
- See principal plus interest
- Annual Breakdown
- Interest by year
The Simple Interest Formula
I = P × r × t, where I is interest, P is principal, r is annual rate, and t is time in years. Unlike compound interest, simple interest is calculated only on the original principal.
Simple vs. Compound
Simple interest grows linearly. Compound interest grows exponentially because you earn interest on interest. Most savings and investments use compound interest.
Questions people ask
When is simple interest used?
Simple interest is common for: auto loans, personal loans, some bonds, and short-term lending. Most savings accounts and investments use compound interest; mortgages charge interest on the remaining balance.
Education only, not personalized financial, tax or investment advice. Results are estimates based on the numbers you enter; real returns vary and losses happen.