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 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?
Interest calculated only on the original principal, not on previously earned interest.
Does it compound?
No. Use the Compound Interest Calculator for compounding.
How are days converted?
Days are converted using a 365-day year for estimation.