Free Civil Litigation Tool
Contract Debt & Interest Calculator
Owed money under a contract? Estimate the outstanding balance plus interest — the total you could claim — by entering the principal, any payments made, the interest rate, and the period the debt has been outstanding.
💰 Your Details
Leave blank if nothing has been paid.
The rate in your contract, or an agreed/estimated rate.
Your Estimate
Enter your details on the left to see your estimate. This tool gives a general estimate only — not legal or financial advice.
Disclaimer: This calculator provides a general estimate using simple interest on the outstanding principal. It does not determine your legal entitlement, does not apply statutory interest rates automatically, and is not legal or financial advice. The interest you can actually claim depends on your contract and the law. Confirm with a lawyer.
Frequently Asked Questions
How is interest on a contract debt calculated?
If your contract specifies an interest rate, that generally governs. Otherwise, prejudgment interest under the Courts of Justice Act may apply at a statutory rate. This tool uses simple interest at the rate you enter on the outstanding principal, which is a common way to estimate what is owed.
Can I charge interest if my contract does not mention it?
You may still be entitled to prejudgment interest under the Courts of Justice Act if you sue, even without a contractual rate. The statutory rate differs from a contractual one. This calculator estimates using a rate you provide; a lawyer can confirm the correct rate for your situation.
Should I include interest in a demand letter?
Often, yes — a demand can include the principal plus interest owed to date. Setting out the calculation clearly signals you are serious and gives the other side a precise figure to pay. Our demand letter guide explains how to structure it.
Is this the amount I can sue for?
It is an estimate of the outstanding balance plus interest, which is typically the core of a debt claim. Your actual claim may also include recoverable costs, and the precise interest entitlement depends on your contract and the law.
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