Financial Calculators
Simple Interest Calculator
Estimate simple interest and the total amount from a principal, annual rate, and time in years locally in your browser.
Enter a principal, annual interest rate, and time in years to estimate simple interest and the total amount. This calculator runs privately in your browser; your numbers are not uploaded or stored.
Estimate simple interest before you borrow or save.
Enter a principal, annual interest rate, and time in years. The calculator uses interest = principal × (annual rate ÷ 100) × years, then adds the interest to the principal for the total amount. This private browser estimate does not include compounding, fees, taxes, or account terms and is not financial advice; your values are not uploaded or stored.
Frequently Asked Questions
Everything you need to know about this tool, how it works, and privacy.
What formula does the simple interest calculator use?
It uses interest = principal × (annual rate ÷ 100) × years. The total amount is principal + interest. For example, $1,000 at 5% for 3 years earns $150 in interest for a $1,150 total.
How is simple interest different from compound interest?
Simple interest applies the rate only to the original principal for the whole period. Compound interest adds earned interest back to the balance, so later periods can earn interest on earlier interest.
Which inputs are accepted?
Enter a principal of zero or more, an annual rate from 0% through 100%, and a time in years of zero or more. Decimal values are accepted, and displayed interest and total amounts are rounded to two decimal places.
Do my values stay private, and is this financial advice?
Yes. The calculation and copy action run locally in your browser, and CodeASystem does not upload or store the values you enter. This is a general estimate, not financial advice.