Judgment Interest Calculator

Post-judgment interest: what a money judgment earns until it is paid

Introduction: why judgments accrue interest and when the clock starts

Winning a money judgment does not put money in your pocket; it starts a second clock. From the moment a court enters judgment, nearly every U.S. jurisdiction lets the award accrue post-judgment interest until the debtor actually pays. The policy is straightforward: without interest, a losing party could profit by dragging out payment, and a prevailing party would be under-compensated for every month of delay. Judgment creditors use the accrual to write payoff letters, judgment debtors use it to price the real cost of waiting, and both sides use it when negotiating installment or settlement terms.

This calculator estimates that accrual between the judgment date and an anticipated payment date. Enter the principal subject to interest, the annual rate from your judgment or statute, the two dates, and a day-count basis, then choose whether interest runs as simple interest (the rule in most state courts, including California and New York) or is compounded annually (the federal rule under 28 U.S.C. 1961 and the rule in a handful of states such as Texas and Michigan). The result shows accrued interest, the total owed, and the per-diem figure that payoff letters quote so the balance can be trued up to the actual date the check arrives.

The judgment interest formula in simple and compounded form

With simple interest, the daily charge never changes because it is always computed on the original principal:

where r is the annual rate as a decimal, Days is the calendar-day count between the judgment date and the payment date, and Basis is the assumed length of a year, 365 days in almost every courtroom or 360 days in some commercial paper. The per-diem charge is the same expression for a single day:

With annual compounding, federal style, accrued interest is folded into the balance on each anniversary of the judgment, so later years earn interest on interest. After n full anniversary years plus d leftover days the payoff is:

Plain-text formula: simple: interest = principal × r × days ÷ basis and per-diem = principal × r ÷ basis; compounded annually: balance = principal × (1 + r)^fullYears on each judgment anniversary, then the remaining partial year accrues balance × r × remainingDays ÷ basis, so total = balance × (1 + r × remainingDays ÷ basis) and interest = total − principal.

Source/version metadata: federal post-judgment rate and annual compounding per 28 U.S.C. 1961 (weekly average 1-year constant maturity Treasury yield, published in the Federal Reserve H.15 release); California rate per Code of Civil Procedure 685.010; New York rate per CPLR 5004; last reviewed July 2026. Verify the governing rate with the judgment, the clerk of court, or counsel.

How post-judgment rates compare across jurisdictions

The single most common mistake with judgment interest is borrowing a rate from the wrong jurisdiction. Federal district courts fix the rate on the day of entry from a Treasury-yield average, so it floats with the market from case to case but stays fixed for that judgment. Many states instead write a flat number into statute, and several carve out lower rates for consumer-debt judgments against individuals. The table below shows how differently six major systems answer the same two questions: what rate, and does it compound?

Treat the table as a map, not an authority: legislatures amend these statutes, contract clauses can displace the statutory rate where the law allows, and some orders specify their own start date or rate. The judgment document itself always controls.

How to use this judgment interest calculator

Start with the judgment or the docket. The principal is the amount the court ordered that is subject to interest, which may include costs and prejudgment interest if the order folds them into the judgment, and excludes anything the order carves out. The annual rate comes from the judgment, the governing statute, or the contract; enter it as a percentage, such as 6 for 6%. The judgment date is normally the date of entry shown on the docket, and the payment date is the date you expect the balance to be satisfied. Pick the interest method your jurisdiction uses, simple for most state judgments or compounded annually for federal-style accrual, and leave the day-count basis at 365 unless your contract or local rule says otherwise.

Read the output as three numbers with three jobs. Accrued interest plus principal gives the payoff as of the chosen date. The per-diem tells you how much each additional day of delay costs, which is the figure to put in a payoff letter so the amount can be adjusted to the day funds actually arrive. And rerunning the calculation with a later fallback date prices the cost of delay itself, useful leverage when negotiating installment plans. For related legal-money questions, the attorney fee split calculator divides contingency fees among counsel and the bankruptcy means test calculator screens Chapter 7 eligibility.

Worked example: a $15,000 judgment at 6% computed both ways

Suppose judgment for $15,000 was entered on March 1, 2024 and the debtor proposes to pay on August 28, 2026, which is 910 calendar days, or two full anniversary years plus 180 days, later.

1. Simple interest. Interest = $15,000 × 0.06 × (910 ÷ 365) = $2,243.84, for a total payoff of $17,243.84. The per-diem is $15,000 × 0.06 ÷ 365 = $2.47 and never changes.
2. Compounded annually. The balance grows to $15,000 × 1.06 = $15,900.00 on March 1, 2025 and to $15,900 × 1.06 = $16,854.00 on March 1, 2026. The final 180 days accrue $16,854 × 0.06 × (180 ÷ 365) = $498.69, so interest totals $2,352.69 and the payoff is $17,352.69. The per-diem in the third year has climbed to $16,854 × 0.06 ÷ 365 = $2.77.
3. The gap. Compounding adds $108.85 over 2.5 years at this size and rate, modest here, but the gap widens fast with bigger principals, higher rates, and longer collection fights.

Enter those inputs above and the calculator reproduces every figure. For a shorter horizon, the same $15,000 at 6% for 180 days accrues $443.84 either way, since compounding only matters once the first anniversary passes.

Assumptions and limitations of this estimate

• Worksheet, not a court filing. The output is an estimate for planning, demand letters, and negotiation. Payoff amounts filed with a court or used to satisfy a judgment should be verified against the judgment, local rules, and the clerk’s calculation.
• One rate, one period. The model assumes a single unchanging rate between the two dates. Florida-style annual adjustments, rate resets, and periods where interest is tolled during appeal or bankruptcy stay must be computed segment by segment.
• Annual compounding only. The compounded option folds interest in on each judgment anniversary, matching the federal convention. It does not model monthly or daily compounding, which almost no judgment statute uses.
• Partial payments not netted. Most jurisdictions apply payments first to accrued interest, then to principal. After any payment, rerun the calculator with the reduced principal from the payment date forward.
• Whole-day counting. Days are counted as calendar-day differences between the two dates, the near-universal convention; the anniversary in a leap year lands on February 28 when the judgment was entered on February 29.
• Scope. Whether interest is allowed at all, which rate applies, whether prejudgment interest or costs also bear interest, and when accrual starts are legal questions this tool does not decide.

Judgment interest questions people ask