Ontario Prejudgment and Postjudgment Interest Calculator
Prejudgment Interest Q1 2026 = 2.5%. Postjudgment Interest Q1 2026 = 4.0%.
Ontario Prejudgment Interest Calculator (s. 128 CJA)
Version 1.1 – Last updated on January 19, 2026.
Ontario Postjudgment Interest Calculator (s. 129 CJA)
Version 1.1 – Last updated on January 19, 2026.
Partial Payments
OptionalIf you (or the other side) made partial payments before the Full Payment Date, add them here, including the payment amount in the first box and the payment date in the second box. Leave empty if paid in full at once.
* This is the date when the legal wrong occurred. For example, this is the date a payment was due but not paid under an agreement.
** This is the date when the Court issued (i.e., put its stamp on) the “Notice of Action” or the “Statement of Claim”, whichever date is earlier.
*** See section 128(1)(4) of the Courts of Justice Act.
**** Postjudgment interest accumulates on the amount the court orders plus costs (as ordered by the court) and the prejudgment interest (if any). See source.
Disclaimer: Use as a reference tool only. Courtready’s Ontario judgment interest calculator does not address (i) prejudgment interest for non-pecuniary damages in personal injury cases under section 128(2) of the Courts of Justice Act and rule 53.10 of the Rules of Civil Procedure, (ii) causes of action for prejudgment interest that arose before Q4 of 1989, and (iii) causes of action for postjudgment interest that arose before Q1 of 1985.
Applicable interest rates are obtained through Ontario.ca. Questions or comments about Courtready’s Ontario judgment interest calculator? Email admin@courtready.ca.
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Frequently Asked Questions
It is the interest a court may add to a damages award from the date the legal wrong occurred to the date of judgment, under the Courts of Justice Act.
It is the interest that accrues on a judgment amount after the court has made its decision and until the money is paid.
It calculates interest using the official quarterly rates published by the Ontario government and the dates you enter (such as the loss date and judgment date).
It calculates how much interest continues to accrue after judgment based on the statutory postjudgment rate and the time until payment.
No. Ontario prejudgment and postjudgment interest rates change every quarter and are set under the Courts of Justice Act based on government-published rates.