How this calculator works
When a court awards money, interest generally starts running on the judgment from its date until it is paid. Unlike contract interest, post-judgment interest is usually simple rather than compounded, and its rate is set by statute or by the court, often at a published benchmark plus a margin. This calculator counts actual calendar days between the two dates and uses a 365-day denominator, the common Actual/365 Fixed basis. Payments are treated as reducing principal from the start, so any interest already accrued when a payment was made is not separated. The rates differ between Canadian provinces and between US federal and state courts, so confirm the rate that applies to your judgment.
Formula
Days = calendar days from the judgment date to the end date, excluding the end date. Daily interest = principal outstanding × annual rate / 365. Accrued interest = daily interest × days. Total due = principal outstanding + accrued interest.
Worked example
A $25,000 judgment awarded on 15 January 2025 at 6% accrues $4.11 a day. To 1 November 2026, 655 days later, the accrued interest is $2,691.78 and the total due is $27,691.78. A $5,000 payment credited at the start would reduce the daily interest to $3.29 and the total due to $22,153.42.
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Frequently asked questions
Is post-judgment interest compounded?
Usually not. Many statutes direct simple interest on the judgment amount. Check the wording that applies, because a few jurisdictions and some contract judgments allow compounding.
Does the 365-day denominator always apply?
Not everywhere. This calculator uses Actual/365 Fixed. Some US federal judgments use a different annualization and some provinces use 365-day counting with specific rules, so a court certificate is authoritative.
How are partial payments handled?
Here they reduce the principal outright from the start. In a real case, payments may be applied first to accrued interest and then to principal, which changes the subsequent interest, so keep a dated payment record.
Can the rate change during the period?
Yes in some jurisdictions. This model holds one rate for the whole period; for a moving rate, calculate each segment separately and add the interest.