Simple Interest Calculator - I = P × R × T Formula
Calculate simple interest (I = P × R × T) for a loan or investment in years, months, or days
How it works
- 1Enter principal and rate
Principal (P) is the amount borrowed or invested. Rate (R) is the annual percentage rate.
- 2Enter time
Enter the duration and pick the unit - years, months, or days.
- 3Read the result
Interest earned or owed, plus the total amount (principal + interest).
About Simple Interest Calculator - I = P × R × T Formula
Free simple interest calculator using the classic I = P × R × T formula. Enter principal, annual rate, and time in years, months, or days to instantly see the interest and total amount. Simple interest applies to short-term loans, some savings accounts, and academic problems where interest does not compound. Runs entirely in your browser. Simple Interest Calculator - I = P × R × T Formula on 712 Tools runs entirely inside your browser using modern JavaScript APIs - no server ever sees your data. That means instant results, complete privacy, and no upload limits.
Whether you need to calculate simple interest (i = p × r × t) for a loan or investment in years, months, or days for a debugging session, a quick sanity check, or a production incident, this tool is free to use as many times as you need. There are no watermarks, no sign-up, and no ads inside the tool itself.
Frequently asked questions
What is the simple interest formula?
I = P × R × T ÷ 100, where P is principal, R is the annual rate as a percent, and T is time in years. Interest is not added to the principal - it does not compound.
How is simple interest different from compound interest?
Simple interest is always calculated on the original principal only. Compound interest is calculated on the growing balance (principal + previously-earned interest), so it grows faster over long periods.
Is my data uploaded?
No. All calculations run entirely in your browser.
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