Unpaid Invoice Calculator

Unpaid Invoice Calculator

Powered by Unpaid Invoice Calculator by Lexscale.ai

Note: this calculator provides a general, informational estimate only — not legal advice about what you'd actually recover.

What This Calculator Actually Does

It totals what's owed on an unpaid invoice — the outstanding balance plus any late fee or interest specified in your original agreement — so you have a concrete figure to work from before sending a demand letter or filing a claim. For the broader picture of how invoice disputes are proven, see unpaid invoices and loans and the deeper side-by-side guide to invoice and loan disputes.

What You'll Need to Use It

• The original invoice, including the amount billed and any payment terms.
• Any partial payments already received, with dates and amounts.
• Any late fee or interest rate stated in your agreement or on the invoice itself.
• The date payment was due, since that's typically when a late fee or interest starts to run.

Late Fees, Interest, and What's Enforceable

A late fee or interest rate you specified upfront — in a contract, quote, or on the invoice itself — is generally something you can include in your claim, provided it was clearly communicated and isn't so high that it looks more like a penalty than a genuine estimate of loss. If your invoice didn't specify any late fee or interest rate, you may still be entitled to prejudgment interest under Ontario law — see the prejudgment interest calculator for that separate estimate.

What to Do With the Result

Once you have a concrete total, a documented demand for payment is usually the next step — see the demand letter builder. If the invoice relates to freelance or gig work specifically, freelance and gig work payment disputes covers issues that come up especially often in that context. If a demand doesn't resolve things, the total from this calculator is a useful starting point for what to claim.

Official sources

• Limitations Act, 2002 — the law governing how long you generally have to sue.
• ontario.ca: Suing Someone in Small Claims Court — the official overview, including the current monetary limit.

Frequently Asked Questions