The federal 85 percent rule: where it comes from and what it misses
The federal "85 percent rule" isn't a rule written anywhere — it's the arithmetic of 18 U.S.C. § 3624(b): 54 days of Good Conduct Time per sentence-year is 54/365 ≈ 14.8%, leaving about 85.2% served. It describes only GCT. First Step Act credits (for eligible people), RDAP early release, and prerelease custody each cut time in prison below 85%. For an eligible, programming person at low PATTERN risk, actual time in a federal prison can run closer to 60–70% of the sentence.
Reviewed against 18 U.S.C. § 3624(b) and 18 U.S.C. § 3624(g). Last updated .
How far below 85% can time in prison actually go?
| Mechanism | Authority | Effect on time in prison |
|---|---|---|
| Good Conduct Time | § 3624(b) | −270 days → ~51 months (85%) |
| FSA credits → supervised release | § 3624(g)(3) | up to −365 days → ~39 months (65%) |
| FSA credits → halfway house / home confinement | § 3624(g) | months more out of the facility |
| RDAP completion (if eligible) | § 3621(e) | up to −12 more months for nonviolent offenses |
| Second Chance Act placement | § 3624(c) | up to 12 months in an RRC at the end |
The mechanisms interact — RDAP time and FSA application overlap in ways that depend on eligibility and circuit law, so the table's rows don't simply add. The OutDate calculator computes the full ladder with the interactions applied and every assumption stated.
Where did people get "85 percent" from, then?
The phrase migrated from state truth-in-sentencing laws (many require 85% served for violent offenses) and stuck to the federal system because the GCT arithmetic happened to land at the same number. Federal law has no parole (abolished by the Sentencing Reform Act of 1984 for offenses after November 1, 1987), so GCT plus the First Step Act mechanisms are the only ways a federal sentence shortens.
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The free OutDate calculator applies these rules to a real sentence — Good Conduct Time, First Step Act credits, halfway house and RDAP dates — with every assumption listed next to the answer. No account needed; nothing is stored.
Open the federal release date calculatorFrequently asked questions
Is there parole in the federal system?
No, not for offenses committed on or after November 1, 1987. The U.S. Parole Commission handles only old-law cases, D.C. Code offenders, and a few other categories. Release timing for modern federal sentences is entirely GCT, First Step Act credits, RDAP, and prerelease custody.
Do violent federal offenses serve more than 85%?
Good Conduct Time applies regardless of offense type, so the ~85% GCT floor is the same. What violent-offense convictions typically lose is First Step Act credit eligibility (18 U.S.C. § 3632(d)(4)(D)) and RDAP early release (28 C.F.R. § 550.55), which is what lets others go below 85%.
Primary sources
Everything on this page is drawn from the statutes, regulations, and BOP program statements below — read them directly:
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Estimates, not promises
This page describes federal law and Bureau of Prisons policy in general terms for education. It is not legal advice, it doesn't account for the facts of any individual case, and no attorney–client relationship is created by reading it. The BOP makes all final release-date determinations. Have an attorney review anything before you file it. Built by OutDate, the federal release date calculator.