How to use the Interest Calculator
This simple-interest tool shows how much interest a fixed rate earns or costs when interest is not compounded.
Open the Interest Calculator →
What you need to enter
- Principal ($)
- Annual interest rate (%)
- Time (years)
The formula
Interest = principal × annual rate × time in years. End balance = principal + interest.
Worked example
Using the default values in the calculator:
- Principal ($): 10000
- Annual interest rate (%): 5
- Time (years): 3
| Total interest | $1,500.00 |
| End balance | $11,500.00 |
Tips for better results
- Use it for short loans, some bonds and quick estimates.
- For savings that compound, use the compound interest calculator instead.
Common mistakes to avoid
- Entering the rate as a decimal (0.05) instead of a percentage (5).
- Using months for the time without converting to years.
Please note: Calculators and guides give general estimates, not financial, tax or investment advice. Real offers depend on your lender, location and personal situation. See our Disclaimer.