Post-Judgment Interest Calculator

A money judgment does not always stay frozen at the number printed in the order. When a debtor pays later, post-judgment interest may be added so the creditor is not left waiting for the same nominal dollars months or years after judgment. This calculator focuses on the arithmetic part: it multiplies the judgment amount by an annual interest rate and by the fraction of a 365-day year that has elapsed. It is useful for checking a payoff request, preparing a writ estimate, comparing settlement timing, or understanding how much a small delay can add.

This page is informational only. It does not decide whether interest is allowed, which balance earns interest, whether costs and fees are included, or which jurisdiction’s rule controls. For federal civil judgments, 28 U.S.C. 1961 sets a statutory framework tied to Treasury yields and refers to interest from the date of entry of judgment. State courts and contracts can use different rates and different conventions. If you need legal rights, deadlines, or a final payoff amount confirmed, check the judgment, the clerk’s instructions, the governing statute, or a qualified lawyer.

How to use the calculator

Enter the judgment amount as the principal balance on which interest should be calculated. If the order says taxable costs, attorney fees, or later awards are included in the interest-bearing balance, include them only if that is the rule you are applying. If partial payments have already been made, reduce the balance first unless your jurisdiction allocates payments in another way.

Next enter the interest rate as an annual percentage. The form expects a rate in percentage points, so 0.14 means 0.14%, not 14%. For a federal judgment, use the rate assigned to the relevant judgment date by the official post-judgment interest table or statute. For a state judgment, use the state statutory rate, contract rate, or court-ordered rate that applies to the case.

Finally choose the date of judgment and the date of writ or payment. The calculation uses the calendar-day difference: the later date minus the earlier date. A same-day payment produces zero elapsed days; a payment date before the judgment date is invalid. The result displays accumulated post-judgment interest, the judgment plus interest, days between dates, daily interest, and the annual rate.

For neighboring money calculations, compare this result with the interest calculator, the simple interest calculator, the percentage calculator, and the savings calculator. Those pages are broader finance tools; this one is deliberately narrow because legal interest often depends on a statutory rate and a specific judgment date.

Formula

The calculator uses simple interest with a 365-day year:

$\text{interest} = \text{judgment amount} \times \frac{\text{annual rate}}{100} \times \frac{\text{days}}{365}$

Then it adds the interest to the entered judgment amount:

$\text{total due} = \text{judgment amount} + \text{interest}$

Daily interest is the annual interest amount divided by 365:

$\text{daily interest} = \frac{\text{judgment amount} \times \frac{\text{annual rate}}{100}}{365}$

The calculator does not compound, does not use a 360-day year, and does not add fees or costs on its own. It also does not round the underlying values before calculating the total; currency formatting rounds the displayed dollars and cents.

Worked example matching the default form

Suppose the judgment amount is $100,000, the annual post-judgment rate is 0.14%, the judgment date is May 24, 2026, and the writ or payment date is June 21, 2026. The date helper counts 28 calendar days between those two dates.

First convert the annual percentage to a decimal rate:

$0.14\% \div 100 = 0.0014$

Then apply the simple-interest formula:

$\text{interest} = \$100{,}000 \times 0.0014 \times \frac{28}{365} = \$10.7397$

Displayed as currency, accumulated post-judgment interest is $10.74. The total judgment plus interest is $100,010.74. Daily interest is:

$\text{daily interest} = \frac{\$100{,}000 \times 0.0014}{365} = \$0.3836$

Displayed as currency, daily interest is $0.38. The copy text would summarize the same computation as $100,000.00 at 0.14% for 28 days equals $10.74 interest.

Why legal interest can differ from the simple result

The simple-interest formula is transparent, but real-world judgment payoff calculations can be more complicated. Federal law refers to interest being computed daily and compounded annually for many federal judgments. Some state rules set one rate for tort judgments and another for contracts. Other rules change after a deadline, use the contract rate until judgment and a statutory rate afterward, or exclude certain costs from the interest-bearing base. A court order can also specify its own treatment.

Partial payments are another common difference. If a debtor pays part of the judgment, the law may say the payment is applied first to costs, then to interest, then to principal, or in some other order. This calculator has no payment schedule field, so it assumes a single principal amount remains outstanding for the whole period. To model a partial payment, run separate simple-interest periods before and after the payment using the appropriate balance for each period.

Rounding can matter when a clerk, sheriff, or attorney prepares a payoff. The calculator formats dollars to cents for readability, but official worksheets may round daily interest, round only at the end, or specify exact cents in an order. If the number will be filed with a court, used in garnishment paperwork, or sent as a demand, verify the local format.

Practical checklist

• Confirm the judgment amount that earns interest.
• Confirm the annual rate and the source of that rate.
• Use the legally correct start date and payoff, writ, or calculation date.
• Check whether the rule calls for simple interest, daily compounding, annual compounding, a 365-day year, or another convention.
• Account for payments, credits, fees, and costs outside this single-period calculator.
• Label the result as an estimate unless it has been approved by the court or the parties.

Sources

• U.S. Courts, Post-Judgment Interest Rate — official federal court page for current and historical post-judgment interest rates.
• Office of the Law Revision Counsel, U.S. House of Representatives, 28 U.S.C. 1961 — federal statute for interest on money judgments in civil cases.