Simple Interest Calculator
Calculate simple interest on a loan or investment. Includes total interest, monthly accrual, and final balance.
Loan or investment
Total after 3 years
$11,500.00
Interest earned
$1,500.00
Per month
$41.67
Principal
$10,000.00
Frequently Asked Questions about the Simple Interest Calculator
What is simple interest?
Interest calculated only on the original principal, not on previously earned interest. Formula: I = P x r x t.
Simple vs compound interest?
Simple interest grows linearly. Compound interest grows exponentially because past interest also earns interest. Over long periods, compound interest produces much higher returns.
Where is simple interest used?
Auto loans, some personal loans, short-term loans, and some bonds. Most savings accounts and credit cards use compound interest.
What is the formula for simple interest?
Interest = Principal x Rate x Time. Total = Principal + Interest. Rate is the annual rate as a decimal; time is in years.
Can I use fractional years?
Yes. 6 months = 0.5 years. The calculator accepts any decimal value.