Simple or Compound? How Judgment Interest Really Grows

The judgment interest calculator computes interest accruing on an unpaid court judgment using simple daily accrual. A crucial detail lurks in how that interest is calculated: whether it is simple or compound, and how the applicable rate is set. These technical choices meaningfully affect how much an unpaid judgment grows over time. Understanding the difference between simple and compound interest in the legal context, and how rates are determined, illuminates the mechanics behind a growing debt owed after a court has ruled.

Two Ways Interest Can Grow

Interest on a debt can accumulate in two fundamentally different ways. Simple interest is calculated only on the original principal, so the same amount accrues each period regardless of how long the debt is outstanding. Compound interest is calculated on the principal plus any interest already accrued, so the interest itself earns interest, causing the balance to grow faster over time. The distinction seems technical but has real consequences, especially over long periods: compound interest can substantially outpace simple interest on the same debt.

The Legal Preference for Simple

Many jurisdictions apply simple interest to post-judgment debts, calculating interest only on the original judgment amount, prorated by the days it remains unpaid. This is the method the calculator uses. Simple interest is straightforward to compute and predictable, and it avoids the accelerating growth of compounding. However, this is not universal; some jurisdictions do compound judgment interest, which would produce a larger total than simple accrual over the same period. Knowing which method applies is essential to computing the true amount owed, and the difference can be significant on a long-unpaid judgment.

Where the Rate Comes From

The interest rate applied to a judgment is not arbitrary; it is set by law. Depending on the court and jurisdiction, the rate may be a fixed figure written into a statute, or it may be tied to a floating benchmark that changes with economic conditions. A statutory fixed rate is stable and known, while a benchmark-linked rate rises and falls over time. This means two judgments of the same amount can accrue interest differently depending on which jurisdiction's rate applies and how it is determined. The rate is a matter of law, not of the parties' choosing.

Computing the Real Balance

These details matter because they determine the actual amount an unpaid judgment grows to. Whether interest is simple or compound, and what rate applies, together shape the balance owed as time passes, which is central to tracking a judgment or negotiating its payoff. The calculator uses simple daily interest and requires the user to supply the applicable rate, since rates and accrual rules vary by jurisdiction. It performs the arithmetic and is not legal advice. Its value is in making the growth of a judgment concrete, while underscoring that the seemingly minor choices of method and rate can meaningfully change what is ultimately owed.

This guide is general educational information about legal concepts, not legal advice. Laws vary by jurisdiction and change over time, and every situation is different. Consult a qualified attorney licensed in your jurisdiction for guidance on your specific circumstances.

For the rationale behind post-judgment interest, see the Legal Interest Calculator; for collecting through wages, the Wage Garnishment Limit Calculator.