Calculating Federal Post-Judgement Interest Calculator

Federal Interest Tool

Estimate post-judgment interest on a federal money judgment using the principal amount, the applicable annual rate, and the time elapsed from the judgment date to the payoff or evaluation date. This calculator applies daily accrual and annual compounding, which reflects the framework commonly associated with 28 U.S.C. § 1961.

How a Federal Post-Judgment Interest Calculator Works

A federal post-judgment interest calculator is designed to estimate the amount of interest that accrues on a money judgment entered in federal court after the judgment date and before the judgment is paid. This is different from pre-judgment interest, contractual default interest, or state-law interest rules that may apply in other settings. In federal cases, post-judgment interest is typically governed by 28 U.S.C. § 1961, which ties the applicable annual rate to the weekly average 1-year constant maturity Treasury yield for the calendar week preceding the date of judgment.

That sounds simple, but the practical calculation can still be confusing. Parties often need to know which rate applies, whether the calculation should be simple or compounded, what date starts accrual, and how to project the balance over time. A strong calculator solves these issues by using a few inputs: the judgment principal, the annual interest rate, the judgment date, and the date through which the balance should be measured. This page then converts the annual rate into daily accrual and reflects annual compounding for long-running judgments.

1 Federal post-judgment interest usually starts from the date judgment is entered.

52 The Treasury yield reference is commonly drawn from the weekly average rate for the week preceding judgment.

365 Many calculations convert the annual rate to daily accrual using a 365-day basis.

Why Post-Judgment Interest Matters

Post-judgment interest exists to compensate the prevailing party for the time value of money after the court has entered a monetary award. If a debtor does not pay immediately, the creditor should not lose economic value during the delay. In that sense, post-judgment interest promotes fairness and encourages prompt satisfaction of judgments.

From a litigation management perspective, the amount can become significant surprisingly fast in larger cases. A modest rate applied to a six-figure or seven-figure judgment over many months can generate a substantial additional obligation. That makes accurate calculation important for settlement discussions, supersedeas bond planning, enforcement strategy, internal accounting, and payoff negotiations.

Key Inputs You Need

• Judgment amount: the principal amount of the money judgment.
• Applicable federal rate: usually the weekly average 1-year constant maturity Treasury yield for the calendar week preceding judgment.
• Judgment date: the date on which post-judgment interest begins to accrue.
• End date: the date of payment, projected payoff, or current evaluation.
• Compounding assumption: federal post-judgment interest is commonly understood to be compounded annually.

The Governing Federal Rule in Plain English

Under federal law, post-judgment interest on a money judgment recovered in a district court is generally calculated using a Treasury-based rate rather than a contractual rate or a prime rate. The statute is intended to create a uniform national standard. The rate is generally determined once, based on the week preceding the judgment date, and then applied throughout the post-judgment period.

The importance of that last point cannot be overstated. Many users mistakenly think the interest rate changes every week or every month as Treasury yields move. For most federal post-judgment calculations, the rate is locked in by reference to the week preceding the judgment. The calculator on this page therefore asks for a single annual rate, not a series of fluctuating rates.

Authoritative Sources

If you want to verify the governing rules or retrieve supporting data, these sources are excellent starting points:

• Cornell Law School Legal Information Institute: 28 U.S.C. § 1961
• U.S. Department of the Treasury: Interest Rate Data
• Federal Reserve H.15 Selected Interest Rates

Simple Example of the Calculation

Suppose a federal court enters a money judgment of $100,000, and the applicable post-judgment interest rate is 5.25% per year. If the judgment remains unpaid for one full year, the first year of accrued interest would be approximately $5,250 on a simple annual basis. If the award continues unpaid beyond a year, federal practice commonly recognizes annual compounding, meaning future interest can accrue on principal plus previously accrued interest after each annual anniversary.

For less than a full year, many calculators estimate interest using daily accrual:

Interest = Principal × Annual Rate × (Days Elapsed / Day Count Basis)

For periods longer than one year, annual compounding can be modeled by applying one year of interest to the balance at each anniversary, then accruing partial-year interest on the updated balance for the remaining days.

Step-by-Step Method

1. Identify the judgment principal.
2. Determine the applicable federal post-judgment rate for the week preceding judgment.
3. Count the number of days from the judgment date to the payoff or target date.
4. Apply daily accrual for each year segment.
5. At each completed year, add accrued interest to the balance to reflect annual compounding.
6. Continue until the end date is reached.

Comparison Table: Effect of Rate and Time on a $100,000 Judgment

Annual Rate	180 Days Approx. Interest	365 Days Approx. Interest	730 Days Approx. Balance with Annual Compounding
2.00%	$986.30	$2,000.00	$104,040.00
4.00%	$1,972.60	$4,000.00	$108,160.00
5.25%	$2,589.04	$5,250.00	$110,775.63
7.00%	$3,452.05	$7,000.00	$114,490.00

The table above uses a $100,000 example and a 365-day basis for illustration. Real results can vary slightly based on exact dates, leap years, local court guidance, and whether partial payments affect the running balance. Still, the table shows the central point: even relatively moderate Treasury-linked rates can create meaningful additional liability when payment is delayed.

Understanding the Treasury Yield Reference

The federal rate is linked to the weekly average 1-year constant maturity Treasury yield. This matters because Treasury yields can move significantly over time. In low-rate environments, post-judgment interest may be fairly modest. In higher-rate environments, the same unpaid judgment can accrue much more quickly.

For example, short-term Treasury yields were exceptionally low during portions of 2020 and 2021, but climbed substantially during 2022 and 2023 as broader interest rates increased. That shift changed the economics of delay in judgment enforcement. A party dealing with a judgment entered during a higher-yield period may face much more substantial interest accumulation than a party dealing with an otherwise similar judgment entered during a near-zero-rate period.

Illustrative Rate Environment Table

Period	Approximate 1-Year Treasury Yield Environment	Interest on $250,000 for 1 Year at That Rate	Practical Effect
Low-rate environment	0.10% to 0.30%	$250 to $750	Post-judgment carrying cost is present but relatively small.
Moderate-rate environment	2.00% to 3.50%	$5,000 to $8,750	Settlement timing and bond planning become more material.
Higher-rate environment	4.50% to 5.50%	$11,250 to $13,750	Delay can materially increase the judgment payoff amount.

Common Mistakes When Calculating Federal Post-Judgment Interest

• Using the wrong rate source. The federal rule generally points to the Treasury-based statutory rate, not a state rate and not necessarily a contract rate.
• Using the current Treasury rate instead of the judgment-week rate. The relevant rate is usually fixed by reference to the week preceding judgment.
• Ignoring annual compounding. Over longer periods, compounding can create a measurable difference.
• Miscounting days. Even small date errors can matter in high-value cases.
• Forgetting partial payments. If any portion of the judgment has been paid, the remaining principal balance may need adjustment.
• Assuming all judgments are treated identically. Appellate decisions, amended judgments, fee awards, and costs can create issues that require legal review.

When You Should Be Extra Careful

Although a calculator is useful, some situations deserve special attention from counsel, a forensic accountant, or a court-approved damages expert. These include cases with amended judgments, post-trial fee awards entered later than the principal judgment, sanctions orders, partial satisfactions, consolidated judgments, bankruptcy overlays, and appellate activity that may alter the effective accrual timeline. If your matter includes one of these features, use a calculator for a working estimate but confirm the final figure with the governing order and applicable precedent.

Use Cases for This Calculator

• Estimating payoff demands for negotiations.
• Modeling interest exposure during an appeal.
• Evaluating reserve requirements and accounting entries.
• Preparing collection correspondence and settlement statements.
• Testing how much delay affects the total judgment balance.

How This Calculator Approaches the Math

This calculator uses a practical framework suitable for many federal post-judgment interest estimates:

1. It accepts a principal amount and annual rate.
2. It counts the days between the judgment date and the selected end date.
3. It accrues interest daily based on the chosen day-count basis.
4. It compounds annually by adding accrued interest to the balance at each completed yearly interval.
5. It reports total interest, ending balance, and average daily accrual.

This approach is useful because it is transparent. You can see the assumptions, adjust the day-count basis for your workflow, and visualize the balance growth on the chart. That makes the tool useful not just for one-off calculations, but also for explaining the result to clients, adjusters, finance teams, and opposing counsel.

Practical Tips for Better Results

• Confirm the exact judgment entry date from the docket, not from memory.
• Pull the correct weekly Treasury yield from an authoritative source.
• Document whether your matter involves any credits or partial payments.
• Retain a screenshot or worksheet for your file in case the estimate is challenged later.
• Recalculate periodically during appeals or enforcement proceedings because the days elapsed continue to grow.

Bottom Line

A federal post-judgment interest calculator can save time and improve accuracy, but only if the inputs are correct. In most standard federal money judgment scenarios, the core ingredients are the principal amount, the Treasury-based statutory rate from the week preceding judgment, the judgment date, and the payoff date. Once those are established, daily accrual with annual compounding provides a reliable estimate of the running balance.

Use the calculator above to model the current amount owed, compare scenarios, and visualize how the balance changes over time. If the numbers will be used in active litigation, a formal payoff demand, or a contested enforcement proceeding, confirm the assumptions against the judgment, the statute, and the relevant case law.

This calculator and guide provide general educational information and an estimate only. They are not legal advice, do not create an attorney-client relationship, and may not capture every issue in a specific case. Always verify the governing rate, dates, and court orders before relying on a final payoff amount.