Legal · Calculator
Ontario judgment interest.
Estimate the prejudgment and postjudgment interest on a money award in an Ontario court, including Small Claims Court. The Courts of Justice Act rates for every quarter are built in, so you only enter dates and dollars. It runs in your browser; nothing you enter is stored or sent.
Inputs
Result
Enter the amounts and dates, then press Calculate interest.
How Ontario court interest works
When a court orders someone to pay money, the winner is usually entitled to two kinds of interest under the Courts of Justice Act. Prejudgment interest compensates for being without the money from the day the cause of action arose until the order is made (s. 128). Postjudgment interest runs from the order until it is paid (s. 129). Prejudgment interest must be asked for in the claim. Both can be replaced by a rate in a contract or another statute, and a judge can change either (s. 130).
The formula
Ontario.ca gives the method: multiply the amount by the rate, divide by 365, multiply by the number of days. Prejudgment uses the rate for the quarter the case started and counts days from the cause of action to the order. Postjudgment uses the rate for the quarter of the order, applies to the award plus costs plus prejudgment interest, and counts days from the order to payment. The prejudgment rate is the Bank of Canada bank rate (first day of the last month of the preceding quarter) rounded to a tenth of a point; the postjudgment rate is that bank rate rounded up to a whole number, plus 1 per cent. The Ministry publishes the resulting table each quarter.
Worked example
Ontario.ca's own example: $40,000 awarded on a claim started in Q1 2021, 60 days from cause of action to order. Prejudgment rate 0.5%: $40,000 × 0.5% ÷ 365 × 60 = $32.88. With $750 in costs, the judgment is $40,782.88. The postjudgment rate for an order in Q1 2021 is 2.0%; paid 60 days later: $40,782.88 × 2.0% ÷ 365 × 60 = $134.08. Enter those figures above to reproduce both numbers.
Recent quarterly rates (per cent a year)
| Year | Q1 pre | Q2 pre | Q3 pre | Q4 pre | Q1 post | Q2 post | Q3 post | Q4 post |
|---|---|---|---|---|---|---|---|---|
| 2026 | 2.5% | 2.5% | 2.5% | 2.5% | 4.0% | 4.0% | 4.0% | 4.0% |
| 2025 | 4.0% | 3.3% | 3.0% | 3.0% | 5.0% | 5.0% | 4.0% | 4.0% |
| 2024 | 5.3% | 5.3% | 5.3% | 4.8% | 7.0% | 7.0% | 7.0% | 6.0% |
| 2023 | 4.0% | 4.8% | 4.8% | 5.3% | 5.0% | 6.0% | 6.0% | 7.0% |
| 2022 | 0.5% | 0.5% | 1.8% | 2.8% | 2.0% | 2.0% | 3.0% | 4.0% |
| 2021 | 0.5% | 0.5% | 0.5% | 0.5% | 2.0% | 2.0% | 2.0% | 2.0% |
| 2020 | 2.0% | 2.0% | 0.5% | 0.5% | 3.0% | 3.0% | 2.0% | 2.0% |
Pre = prejudgment, by quarter the case was started. Post = postjudgment, by quarter of the order. The calculator holds the full published tables (prejudgment from late 1989, postjudgment from 1985).
What this does not do
It does not handle contract or statutory rates, personal-injury non-pecuniary damages (rule 53.10), the six-monthly calculation for past pecuniary loss under s. 128(3), the exclusions in s. 128(4), partial payments, or a judge's discretion under s. 130. Interest is not owed on money already paid, so for part payments calculate each period separately, as the official page shows. This page covers Ontario only.
Sources
- Government of Ontario: Prejudgment and postjudgment interest rates: quarterly rate tables, method and worked examples (page updated September 2, 2026).
- Courts of Justice Act, R.S.O. 1990, c. C.43, ss. 127-130: definitions of the rates, entitlement, exclusions and court discretion.
Rates and rules as read from the sources above on October 1, 2026. Check the official page for any later quarter.
Cite this page: TNAADO Tools. “Ontario Judgment Interest Calculator.” tools.tnaado.ca/legal/ontario-judgment-interest-calculator/. Rates from the Government of Ontario, as of September 2, 2026. Accessed October 1, 2026.
Frequently asked questions
Which rate applies to prejudgment interest in Ontario?
The Courts of Justice Act rate for the quarter in which the proceeding was commenced (the date the court issued the claim), not the quarter of the judgment. It is the Bank of Canada bank rate on the first day of the last month of the preceding quarter, rounded to the nearest tenth of a point (s. 127(1)).
Which rate applies to postjudgment interest?
The rate for the quarter in which the order was made: the bank rate rounded up to the next whole number, plus 1 per cent (s. 127(1)). It stays fixed for that order even if the quarterly rate later changes.
From when does interest run?
Prejudgment interest runs from the date the cause of action arose to the date of the order (s. 128(1)). Postjudgment interest runs from the date of the order until the money is paid (s. 129(1)), on the amount ordered plus costs and prejudgment interest.
Does this apply in Small Claims Court?
Yes. Ontario.ca says the same Courts of Justice Act rates and the same method apply in a Small Claims Court lawsuit, where the case starts when the plaintiff's claim is issued. You must ask for prejudgment interest in your claim.
When does this calculator give the wrong answer?
Whenever something other than the simple method applies: a contract or statute that sets its own rate, personal-injury non-pecuniary damages (rule 53.10), past pecuniary loss calculated six-monthly under s. 128(3), amounts excluded by s. 128(4), partial payments, or a judge using the discretion in s. 130 to change the rate or period. It is an estimate, not legal advice.
What about British Columbia and other provinces?
This page covers Ontario only. Other provinces set court interest under their own statutes and publish their own rates; none are included here because they have not been checked against a primary source for this page.
What a result does and doesn’t tell you
This is an estimate using the standard Courts of Justice Act method, not legal advice and not what a court will necessarily order. The judge or a court clerk sets the actual amount. Everything runs in your browser and nothing is stored or sent.