Calculator, checked in 2026
Interest calculator
Estimate simple interest on an unpaid amount between two dates at a rate you enter.
Rules last checked in 2026. General information only.
Enter the unpaid amount, the annual rate and the two dates. The tool shows simple interest for the period and the total with interest.
Contracts often set their own interest rate, and courts apply separate rules for prejudgment and post-judgment interest. This tool does not pick a rate; it only does the math for the rate you enter.
This content is general information, not legal advice. Deadlines and rules change and vary by state; your situation needs to be reviewed with your documents.
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