US Late Payment Interest Calculator

Estimate interest on late payments in the United States using a custom annual rate. Results are estimates for convenience and not legal advice.

How late payment interest works in the US

In the US, late payment interest can be based on contract terms, invoice terms, or state-specific rules depending on the situation. This calculator lets you apply an annual rate you choose and estimate interest over a date range.

Tip: If you have a contract or invoice that specifies an interest rate (or late fee), use that rate here.

Amount owed

Annual interest rate (%)

Start date

End date

Interest type

Currency

Method: simple interest or daily compounding. Always confirm the correct method and rate for your contract or jurisdiction.

Results

Days overdue

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Interest

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Total

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How it’s calculated

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FAQ

What interest rate should I use?

Use your contract or invoice rate if specified. If not, you may need to check applicable rules for the type of debt and the relevant state.

Is this legal advice?

No. This calculator provides an estimate only.