Simple Interest Calculator
Enter a principal amount, interest rate, and time period to calculate simple (non-compounding) interest and the total amount due or earned — the straightforward formula used for many short-term loans.
All calculations happen on your device — no financial figures are sent to a server.
Simple interest is calculated only on the original principal for the whole term, unlike compound interest, which is calculated on the accumulated balance — a completely different mathematical model.
What this tool does
Calculates simple interest on an amount over a term at an annual rate — interest on the principal alone, with no compounding — giving the interest and the total.
When to use it
- A loan or agreement whose interest is charged on the principal only.
- Comparing simple against compound interest for the same amount and term.
- An educational calculation or a coursework exercise.
How to use it
- Enter the principal amount.
- Enter the annual rate and the term in years.
- Run the calculation and read the interest and the total.
A practical example
Input
An amount at an annual rate over three years.
Output
The interest and the total due — both lower than compound interest would give for the same inputs.
Limitations
- Most real loans and deposits use compound rather than simple interest; check which applies to your case.
- This is for information and is not financial advice.
- It excludes any additional fees.
Privacy and processing
The principal, rate and term are computed locally and never leave your device.
Technical notes
- Simple interest is charged on the principal throughout, so it grows linearly, unlike compound interest which grows exponentially.