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LegalCalc Ontario
Ontario Calculator

Ontario Court Interest Calculator

Estimate simple interest on an Ontario court matter under sections 127–130 of the Courts of Justice Act. Choose prejudgment, postjudgment, or custom simple interest. Confirm the applicable rate against the official quarterly table before relying on any figure.

Inputs

All amounts in Canadian dollars (CAD).

Calculation type

The statutory prejudgment rate under s 127 is generally determined by reference to the quarter in which the proceeding was commenced, subject to sections 127–130, any statutory exceptions (for example, non-pecuniary damages or specialty debts), and the court's discretion. Contracts and orders can also fix a different rate.

Check Ontario court interest rates (opens in a new tab)

Used to identify which quarter's published rate you should confirm. It does not change the calculation below.

Days are counted as calendar days between the two dates (end date minus start date). A one-year period that includes 29 February is 366 days.

Payment allocation assumption

The applicable order, agreement, or enforcement rules may specify the order. Change the assumption to match the governing document.

Payments made
Optional. Reduces the running balance.

Result - Prejudgment interest

Formula: Interest = Principal × Rate × (Days ÷ 365). Simple interest, calculated on the outstanding principal only.

Fix the highlighted issues above to see the calculation.

Estimate only
Calculations are estimates. Laws, rates, and rules can change. Obtain professional legal or financial advice before relying on any result.

About this calculator

In Ontario, interest on money judgments is governed by sections 127–130 of the Courts of Justice Act. Prejudgment interest generally runs to the date of the order at a rate tied to the quarter in which the proceeding was commenced, subject to statutory exceptions and to the court's discretion. Postjudgment interest generally runs from the order date at a rate tied to the quarter of the order.

Section 127 provides for simple interest - not compound - calculated on the outstanding principal. A contract or order may fix a different rate, and the court may adjust interest under sections 129 or 130 in appropriate circumstances.

This tool computes simple interest on the exact number of calendar days between the dates you provide, using a 365-day denominator. Rate lookups and legal characterisation (for example, whether a claim is for non-pecuniary damages) should be confirmed against the statute and the Ministry's published rate table.

Worked example

Facts. A judgment for $10,000 at 5.0% per annum simple, calculated for a full calendar year that includes a leap day (366 days).

Calculation. $10,000 × 5.0% × (366 ÷ 365) ≈ $501.37.

Balance owing. $10,501.37, subject to any payments credited during the period.

Frequently asked questions

Official sources

Last reviewed: 19 July 2026Spotted an error? Suggest a correction →