Judgment Interest Calculator
A free tool for computing the judgment interest that accrues on an award. Enter the principal, pick a statutory rate, and total the prejudgment or post-judgment interest in seconds — simple or compound, on any date range. No signup, nothing to install.
Note: the state rates above are illustrative defaults that change periodically and may float against an index. They are informational, not legal advice — verify the current rate and method against the governing statute before you rely on them.
$100,000.00 principal × 9% over 206 days (365-day basis, simple) = $5,079.45 interest, for a total of $105,079.45.
For informational purposes only. Verify the rate, method, and accrual rules for the jurisdiction and claim type before relying on any figure — this calculator is not legal advice and does not create an attorney–client relationship.
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How to calculate judgment interest
To calculate judgment interest, multiply the principal by the annual statutory rate and then by the fraction of the year the award has been outstanding. A judgment interest calculator turns that into one step: enter the amount, the rate, and the date range, and it returns the interest accrued and the running total.
The starting point matters. Prejudgment interest compensates the plaintiff for the delay between the loss or filing and the date judgment is entered, while post-judgment interest runs from entry until the judgment is paid. Each can carry a different rate and method, so check which one applies before you compute.
Simple interest accrues only on the original principal, so it grows in a straight line. Compound interest reinvests the accrued interest each period, so the balance grows on itself — faster, and only where the statute allows it. Because these rates are statutory, they are fixed by law rather than negotiated, and many states peg them to a treasury or prime index that resets periodically.
Frequently asked questions
- How do you calculate judgment interest?
- Multiply the judgment principal by the annual statutory rate, then by the number of days the judgment has been outstanding divided by the day-count basis (365 or 360). For simple interest the result is principal × rate × days / basis. Compound interest reinvests the accrued interest each period, so it grows on the running balance instead of just the original principal.
- What is the difference between prejudgment and post-judgment interest?
- Prejudgment interest compensates the plaintiff for the time between the loss or the filing and the date judgment is entered. Post-judgment interest accrues from the date the judgment is entered until it is paid in full. The rate, the method, and the start date for each are set by the governing statute and can differ.
- Is judgment interest simple or compound?
- It depends on the jurisdiction. Many states and the federal courts apply simple interest to post-judgment awards, while some allow annual compounding. Always confirm the method in the controlling statute, because using compound interest where only simple is allowed will overstate the balance.
- Are the statutory rates in this calculator accurate?
- The state rates are illustrative defaults to get you started. Statutory interest rates change periodically, some float against a treasury or prime index, and the method can vary by claim type. Treat the figures as informational only and verify the current rate and accrual rules against the governing statute before relying on them.