simple interest = principal × rate × timeLoan and investment results are estimates. Confirm fees, compounding frequency and the lender’s actual schedule.
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Simple interest calculator
Calculate simple interest from principal, annual rate and time.
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This tool runs on your device in the browser.
Instructions and limitations
TOOL GUIDE
What this tool is for
Simple interest calculator — Calculate simple interest from principal, annual rate and time.
Useful for quick everyday estimates and for checking arithmetic with clearly entered values.
Common uses
- Check everyday arithmetic
- Compare possible values
- Create a quick estimate
Educational and informational use
Results are general estimates, not legal, financial, tax, medical, engineering, or other professional advice. Check inputs and units and consult a qualified professional for important decisions.
EXPLANATION & EXAMPLE
Understand the result—not just the number
$1,000 at 5% for 2 years → $100 simple interestAfter calculating, the tool shows the values used and the working so you can check it.