For Q1 and Q2 of 2026, the Ontario prejudgment interest rate under section 128 of the Courts of Justice Act is 2.5%, and the Ontario postjudgment interest rate under section 129 is 4.0%. The rates are set quarterly by the Ministry of the Attorney General and published by the Government of Ontario. This Ontario judgment interest calculator uses the full set of statutory quarterly rates from 1985 to the current quarter.

Ontario prejudgment interest is calculated under section 128 of the Courts of Justice Act. The rate is the prejudgment rate for the quarter in which the proceeding was commenced, not the quarter when the cause of action arose. Interest runs from the date the cause of action arose to the date of the order. The formula is: award amount × rate% ÷ 365 × number of days. Prejudgment interest does not apply to non-pecuniary damages in personal injury cases, which are governed by rule 53.10 of the Rules of Civil Procedure.

Ontario postjudgment interest is calculated under section 129 of the Courts of Justice Act. The rate is the postjudgment rate for the quarter in which the order was made, and that rate stays fixed even if payment spans multiple quarters or years. Interest runs from the date of the order to the date of payment. Where the debtor makes partial payments, interest is calculated separately for each period on the unpaid balance. This Ontario postjudgment interest calculator handles partial payments automatically.

Prejudgment interest compensates the plaintiff for being out of pocket between the date the cause of action arose and the date of the judgment. It is governed by section 128 of the Courts of Justice Act. Postjudgment interest compensates the plaintiff for delay in payment after the judgment is issued, and is governed by section 129. The two use different statutory rate tables, and the postjudgment rate is typically about 1.5% higher than the prejudgment rate for the same quarter.

No. Under subsection 128(2) of the Courts of Justice Act, the statutory prejudgment interest rate does not apply to non-pecuniary loss in personal injury actions. The rate for that head of damages is set by rule 53.10 of the Rules of Civil Procedure, which is updated quarterly by the Civil Rules Committee. This Ontario prejudgment interest calculator should not be used for non-pecuniary damages in personal injury cases.

Yes. The Ontario Judgment Interest Calculator is completely free, with no account, login, or payment required. It is provided by Courtready as a public legal education resource. It is a reference tool only and does not constitute legal advice. Users should always verify the applicable rate against the Government of Ontario published rate tables and the current version of the Courts of Justice Act.