Calculation method
For a commercial invoice, the tool applies principal × annual rate ÷ 100 × overdue days ÷ 365. Use only a rate and day count you have already verified from the contract and the law that applies to the claim.
Worked example
A USD 25,000 invoice at a verified 8% annual simple-interest rate for 90 overdue days produces USD 493.15: 25,000 × 0.08 × 90 ÷ 365. This arithmetic does not establish that the rate is recoverable.
What the result excludes
This tool does not supply a statutory or contractual rate, compound interest, tax penalties, credit-card interest, loan interest, collection costs or a conclusion about recoverability. Confirm the claim, governing terms, applicable law, rate, day-count basis and any payments or credits before relying on the arithmetic.
Reference point
UNIDROIT Principles of International Commercial Contracts 2016. A non-binding general contract reference that discusses interest on non-payment. It does not supply this calculator's rate or determine whether the Principles, interest, or any particular rate applies to a claim.
What this tool does
It turns user-supplied choices or scenario numbers into a preparation snapshot. It does not inspect private documents, make a legal determination, select a jurisdiction, or replace advice based on the full facts.
Privacy and data boundary
The tool runs in your browser. Do not enter personal, sensitive, confidential, or privileged information. JurisLane records only the fixed tool identifier when an allowed analytics event runs; answers, amounts, and results are excluded.
Important limitation
Public tools provide general information and preparation support, not legal, tax, employment, financial, regulatory, or recovery advice. Verify official rules and obtain qualified support before acting.