Free Financial Calculator
Simple Interest Calculator
Calculate interest earned on a principal amount without compounding.
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Complete the fields and select Calculate to view the estimate.
How This Calculator Works
Simple interest uses the formula I = P × r × t, where P is principal, r is the annual rate as a decimal, and t is time in years. Months and days are converted to a year fraction.
Frequently Asked Questions
What is simple interest?
Simple interest is calculated only on the original principal, not on previously earned interest.
Does this calculator compound interest?
No. Use the Compound Interest Calculator for compounding.
How are days converted?
Days are converted using a 365-day year for estimation.