Good time in jail is a reduction of your sentence that you earn by following the rules and, in many facilities, by participating in work or programs. The amount you can earn depends entirely on which system is holding you: county jails, state prisons, and the federal Bureau of Prisons each use their own formula, and the difference between them can be months or years on the same sentence.
How You Earn Good Time
The baseline is behavior. Every system starts from the same place: follow the rules, avoid fights, cooperate with staff, and don’t rack up disciplinary infractions. In most facilities, that passive compliance alone generates a steady stream of credit. The federal Bureau of Prisons uses the phrase “exemplary compliance with institutional disciplinary regulations,” which in practice means no serious rule violations during the crediting period.1Office of the Law Revision Counsel. 18 USC 3624 – Release of a Prisoner
Beyond staying out of trouble, most systems let you earn additional credit through approved programs:
- Educational courses, including GED preparation, literacy classes, or college coursework. The federal system specifically considers whether an inmate is making progress toward a high school diploma or equivalent.1Office of the Law Revision Counsel. 18 USC 3624 – Release of a Prisoner
- Vocational training in trades like welding, carpentry, or computer skills.
- Substance abuse treatment, including counseling and residential programs.
- Institutional work assignments such as kitchen duty, maintenance, or janitorial work.
What’s actually available depends on where you are. A large state prison may offer dozens of programs; a small county jail may have little beyond a work assignment. Some facilities provide programs free, others deduct fees from your commissary account.
How Much Time It Takes Off
There is no single national formula. Federal, state, and county systems each calculate credit differently.
Federal Good Conduct Time
Federal inmates serving sentences longer than one year, but not life, can earn up to 54 days of good conduct time for each year of the sentence the judge imposed.1Office of the Law Revision Counsel. 18 USC 3624 – Release of a Prisoner That distinction matters: the First Step Act of 2018 changed the calculation from time served to time imposed, which meaningfully expanded credit-earning potential.2Federal Bureau of Prisons. First Step Act Overview
Under the current formula, a 10-year federal sentence could earn up to 540 days off, roughly 15 percent. A five-year sentence could earn up to 270 days. These are ceilings. The Bureau of Prisons decides each year whether your conduct qualifies for the full 54, a reduced amount, or nothing at all, and credit not earned in a given period cannot be added back later.1Office of the Law Revision Counsel. 18 USC 3624 – Release of a Prisoner
State Prison Systems
State formulas are all over the map. Some use a flat rate, awarding a set number of days for every 30 served without incident. Others use day-for-day credit, where each day of good behavior takes off another day and effectively cuts the sentence in half. Others use tiered structures based on offense type or classification level, with rates that can be as restrictive as one day off for every six served, or as generous as 75 days off for every 30 served at the top classification.
The impact is enormous. Under day-for-day, a one-year sentence can be finished in roughly six months. Under a one-for-three rule, it drops by about three months. The rates are set by state statute and applied by the department of corrections, not by the sentencing judge.
County Jails
People asking about jail good time are often in a county or local facility rather than a state prison, and the rules can differ substantially even within one state. County jails house people serving shorter sentences, often a year or less for misdemeanors, and the credit system is generally set by state law but administered locally by the sheriff or jail superintendent.
Rates vary widely. Some jurisdictions offer day-for-day credit on misdemeanor sentences, so a 12-month sentence can end after about six months of clean behavior. Others give a fixed percentage reduction, such as a quarter off. Many jails add extra credit for work assignments or educational classes on top of the baseline behavior credit.
One thing catches people off guard: very short sentences may not qualify for good time at all, or the arithmetic produces only a trivial reduction. A 30-day sentence in a system awarding 10 days per 30 saves 10 days, and that’s it.
Earned Time Credits Under the First Step Act
Federal inmates have access to a second, separate credit that works differently from good conduct time. The First Step Act created earned time credits for participating in recidivism-reduction programs and productive activities, and these stack on top of the 54-day-per-year good conduct time.3Office of the Law Revision Counsel. 18 USC 3632 – Development of Risk and Needs Assessment System
The earning rate is 10 days of credit for every 30 days of successful program participation. Inmates assessed as minimum or low risk for reoffending who maintain that status across two consecutive assessments earn an extra 5 days per 30, for a total of 15 days per month of programming.3Office of the Law Revision Counsel. 18 USC 3632 – Development of Risk and Needs Assessment System
One important distinction: earned time credits are applied toward transfer to prerelease custody, such as a halfway house, or to supervised release, rather than directly shortening the prison sentence the way good conduct time does.3Office of the Law Revision Counsel. 18 USC 3632 – Development of Risk and Needs Assessment System The result is still an earlier departure from prison, but the transition is to community supervision rather than full release.
The 85 Percent Cap and Other Limits
Good time credit doesn’t operate in a vacuum. Many jurisdictions have truth-in-sentencing laws that cap how much any credit can reduce a sentence. The most common threshold is 85 percent: no matter how much good time you’ve built up, you must serve at least 85 percent of the imposed sentence.
This spread nationally after Congress passed the Violent Crime Control and Law Enforcement Act of 1994, which offered federal grant money to states that required people convicted of serious violent crimes to serve at least 85 percent. By the end of the 1990s, more than 40 states had adopted some version of the requirement.4National Institute of Justice. Truth in Sentencing and State Sentencing Practices Some states have since scaled back their versions, but the 85 percent floor remains widespread for violent offenses.
The practical effect: even in a state with day-for-day credit, someone convicted of a violent felony may be required to serve 85 percent regardless of behavior. The credit system technically still runs, but the cap overrides it. For nonviolent offenses, the cap often doesn’t apply or is set lower, which is why credit rates appear to swing so widely by conviction type.
Pretrial Credit Is Not Good Time
Two very different credits get confused constantly. Good time is earned through behavior after sentencing. Pretrial credit, sometimes called jail credit or time served, is automatic credit for days you spent locked up before your case was resolved.
Federal law requires that a defendant receive credit toward the sentence for any time in official detention before the sentence begins, as long as that time hasn’t already been credited against another sentence.5Office of the Law Revision Counsel. 18 USC 3585 – Calculation of a Term of Imprisonment Most states have equivalent rules. Four months awaiting trial before a one-year sentence means those four months count toward the year.
The two credits work together. Pretrial credit reduces the total time you need to serve, and good time reduces what remains. Getting either one wrong produces an inaccurate release date, which is one of the most common sources of frustration for inmates and their families.
Who Doesn’t Qualify
Not everyone is eligible. The most common disqualifier is the nature of the conviction. Both federal law and most state systems exclude certain serious offenses from credit eligibility or sharply limit the accrual rate.
In the federal system, First Step Act earned time credits are unavailable to inmates convicted of a long list of disqualifying offenses, including terrorism, serious sexual offenses, offenses involving minors, murder, kidnapping, and various weapons and national security crimes.6Federal Bureau of Prisons. Good Time Disqualifying Offenses Good conduct time under 18 U.S.C. ยง 3624 is broader but still excludes anyone serving life.1Office of the Law Revision Counsel. 18 USC 3624 – Release of a Prisoner
Other factors that affect eligibility:
- Sentence length. Federal good conduct time requires a sentence of more than one year, and some state and local systems similarly exclude very short sentences.1Office of the Law Revision Counsel. 18 USC 3624 – Release of a Prisoner
- Mandatory minimums. In many jurisdictions, good time cannot take you below a mandatory minimum term set by statute.
- Housing and classification. Inmates in disciplinary segregation or other restrictive housing may not earn credit while in that placement.
- Immigration detainers. Federal inmates with pending immigration holds may face complications in applying earned credits toward prerelease custody.
These restrictions apply no matter how well someone behaves. A person convicted of a disqualifying offense can have a spotless record and still be ineligible, because the determination turns on the conviction itself.
How You Lose Good Time
Credits built up over months can be taken away in a single disciplinary incident. Infractions that commonly trigger forfeiture include fighting, possessing contraband such as drugs or weapons, failing a drug test, or refusing staff orders. The more serious the violation, the more credit you can lose.
The Federal Disciplinary Process
In the federal system the process begins with a staff-issued incident report, which the inmate normally receives within 24 hours, describing the alleged violation and the specific rule broken.7eCFR. 28 CFR Part 541 – Inmate Discipline and Special Housing Units
A Unit Discipline Committee reviews the report within five working days. It can impose certain sanctions but cannot take away good conduct time. Serious violations get referred to a Discipline Hearing Officer, who conducts a formal hearing and has the authority to revoke earned credit. Loss amounts scale with severity: the most serious violations carry a mandatory minimum loss of at least 41 days or 75 percent of available credit for the period, whichever is less. High-severity offenses cost at least 27 days or 50 percent.7eCFR. 28 CFR Part 541 – Inmate Discipline and Special Housing Units
Due Process Before Credits Can Be Taken
The U.S. Supreme Court has held that inmates have due process rights before good time can be revoked. Under Wolff v. McDonnell, the minimum requirements are advance written notice of the charges at least 24 hours before the hearing, the right to call witnesses and present documentary evidence (unless doing so threatens institutional safety), and a written statement from the decision-maker explaining the evidence and reasons.8Justia US Supreme Court. Wolff v. McDonnell, 418 US 539 (1974)
The evidentiary bar is low. In Superintendent v. Hill, the Court held that revoking good time credits satisfies due process as long as “some evidence” supports the finding. Courts don’t reweigh evidence or reassess witness credibility. If anything in the record could support the conclusion, the standard is met. That is where most challenges to forfeiture collapse.
Getting Credits Back
In the federal system, revoked credits can potentially be restored, though the Bureau of Prisons has discretion over whether and when.9Federal Register. Good Conduct Time Credit Under the First Step Act State and local systems vary. Some allow the warden or jail administrator to restore credit after a period of sustained good behavior; others treat forfeiture as permanent.
Challenging a Denial or Forfeiture
If you believe credits were wrongly denied or improperly revoked, there are avenues to challenge the decision, though the process is slow. In the federal system, the Bureau of Prisons requires you to raise the concern informally with staff first. If that doesn’t resolve it, you file a formal Request for Administrative Remedy.10Federal Bureau of Prisons. Administrative Remedy Program This internal grievance process typically has to be exhausted before a federal court will hear the claim.
State and local jails have their own grievance procedures, which vary widely in formality. The constitutional floor is the same everywhere: the Wolff v. McDonnell due process protections apply nationwide.8Justia US Supreme Court. Wolff v. McDonnell, 418 US 539 (1974) If you were denied a hearing, weren’t given written notice, or weren’t allowed to present evidence before losing credits, those are the strongest grounds. Simply disagreeing with the outcome, when the procedures were followed, is a much harder fight given the minimal “some evidence” standard the institution has to meet.