Sentence, Good-Time Credit & Release Date Calculator
Estimate a projected release date from the sentence, jail credit and good-conduct time — federal 54 days a year with First Step Act credits and RDAP, or a state percentage, days-per-month credit, truth-in-sentencing floor and parole eligibility — with pre-release dates and time left.
How it works
Sentence days = calendar days from the start date to start + years + months + days · Federal good time = 54 × years imposed (terms over one year only) · State: credit = sentence × % or sentence − sentence ÷ (1 + credit days ÷ 30) · Time to serve = max(sentence − good time, sentence × minimum %) · Days to release = time to serve − jail credit − RDAP − First Step Act credits (≤ 365) · Release = start + days to release · Full term = start + sentence − jail credit · Pre-release starts = release − pre-release months − extra FSA credits
A sentence pronounced in court is rarely the time actually spent in custody. Jail credit subtracts the days already held before sentencing; good-conduct time — 54 days per year of the sentence imposed in the federal system since the First Step Act, and anywhere from 15% to 50% in the states — is earned for staying out of trouble; but many states impose a floor, such as the 85% truth-in-sentencing rule for violent offences, below which no credit can take the release date. Some states award credit as a percentage of the sentence, others as a number of days for every 30 days served; day-for-day credit halves the time served. In the federal system, eligible prisoners can also earn First Step Act time credits — 10 days, or 15 for minimum and low risk, for every 30 days of programming. Up to 365 of them bring the release date forward and the rest move transfer to a halfway house or home confinement earlier. Completing RDAP can take off up to a further 12 months. Pre-release custody comes off the end. The arithmetic here reproduces the structure of a sentence computation; the real one is done by the correctional agency under its own statutes, and parole eligibility in a state system is only a date on which release may be considered.
Worked example
A 5-year federal sentence starting March 1, 2025 runs 1,826 days to March 1, 2030 and earns 54 × 5 = 270 days of good time, leaving 1,556 days to serve (85%). With 120 days of jail credit, 1,436 days remain from the start date — release about February 4, 2029 — with halfway-house eligibility roughly six months before that. With First Step Act credits at 15 days per 30 the full 365-day reduction applies, bringing release to about February 5, 2028 (2028 is a leap year), and the extra credits move pre-release custody earlier still. Forfeiting all good time would push release to the full 1,706 remaining days.
Sources: 18 U.S.C. § 3624 — Release of a prisoner (Cornell LII) · 18 U.S.C. § 3632 — First Step Act time credits (Cornell LII)
Frequently asked questions
How is federal good time calculated now?
Since 2019, 54 days for each year of the sentence imposed (prorated for partial years), on terms of more than one year; a sentence of 12 months or less earns none, which is why “a year and a day” is sometimes imposed. Previously the BOP’s method gave about 47 days per year. Good time can be lost for disciplinary infractions.
How do First Step Act credits change the release date?
Eligible prisoners earn 10 days for every 30 days of approved programming, or 15 days at minimum or low recidivism risk. Up to 365 days can be applied to an earlier transfer to supervised release; credits beyond that move the transfer to a halfway house or home confinement earlier. Some offences are excluded, and the BOP applies credits after risk reassessments.
What about state systems?
They vary enormously: some award day-for-day credit (50%), some one day for every two served, some only 15% for violent crimes; many have truth-in-sentencing floors of 85%, and others keep discretionary parole at one quarter, one third or one half of the sentence. Choose the percentage or days-per-month rule, set the floor and parole share, and use the state’s own rules for anything beyond an estimate.
What is the difference between the release date and the full-term date?
The full-term date is when the whole sentence would end with no good time at all (less jail credit). The projected release date assumes all available good time is earned and kept; losing good time for misconduct moves it back toward the full-term date.
Does jail credit count toward the sentence?
Usually yes: days held in custody before sentencing on the same charge are credited toward the sentence, so they come off the time left to serve. Federal credit is decided by the BOP under 18 U.S.C. § 3585(b), and time already credited to another sentence does not count twice.
Related calculators
General-information arithmetic based on common US practices; statutes, court rules, fee schedules and credit rules differ by jurisdiction and change over time. This is not legal advice — confirm with a licensed attorney or the court.