Free tool for freelancers and small shops. Enter the overdue amount, the monthly late fee rate from your contract, and how many months it is overdue. The calculator uses simple interest: late fee = amount × monthly rate × months overdue.
Example shown on load: $1,200 × 1.5% × 2 months = $36.00 late fee, $1,236.00 total due. This tool is not legal advice and does not replace your contract. Always check what your contract and local rules allow before charging a late fee. This page runs entirely in your browser and does not save or send your numbers.
If late payments keep happening, use a tracker instead of chasing them from memory:
Free calculator. No sign-up, no account, no payment needed to use it.