Late Payment Fee Calculator

Enter an overdue invoice, your monthly late fee rate and the days past due. You get the late fee and the new balance. Everything runs in your browser; nothing is stored or sent.

How it works

Late fee = unpaid amount × monthly rate × (days past due ÷ 30). Example: $1,500 × 1.5% = $22.50 a month; 45 days is 1.5 months, so $33.75, and the new balance is $1,533.75. The 1.5% default is illustrative. Many states cap late fees or interest, and a fee generally needs to be stated in your contract or invoice terms beforehand, so check local rules.

Next step: protect your cash flow with the deposit & payment schedule calculator.

Estimates for planning only. This is not accounting, tax or legal advice.