Figure the late fee on an overdue invoice. Enter the invoice amount, your monthly late fee rate, and how many months overdue — and see the fee and the new total owed.
A simple (non-compounding) monthly late fee. Late fees are regulated — many states cap the rate and require the fee to be stated in your contract. Confirm what's allowed where you operate.
Multiply the invoice amount by your monthly late-fee rate, then by the number of months overdue. A $1,000 invoice at 1.5% per month, two months late, is a $30 fee — $1,030 owed.
Late fee = invoice × monthly rate × months overdue
Late fees must be disclosed in your terms and can't exceed state limits, so set a rate you can actually enforce.
Commonly 1–2% of the invoice per month (or a small flat fee), but many states cap the maximum. Always state the fee in your contract or invoice terms before you charge it.
Multiply the balance by your monthly percentage and by the months overdue. This tool does it and shows the new total owed.
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Yes. The Late Fee Calculator is completely free, runs in your browser, and never asks for a signup, email, or download. Enter your numbers and the result updates instantly.
It uses standard formulas and recalculates the moment you change a value, so the math is exact for the inputs you enter. Treat the result as a reliable planning estimate; for decisions with legal or tax consequences, confirm the figures with a qualified professional.
Yes. The calculator is mobile-friendly and works on any phone, tablet, or computer — there is no app to install and nothing to save.
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Last reviewed: September 2026. Free to use, no signup — Late Fee Calculator by ToolWise Digital.
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