Our Methodology

Our calculator uses the release fractions in the Criminal Justice Act 2003, as amended by section 23 of the Sentencing Act 2026 and as modified by the Criminal Justice Act 2003 (Requisite and Minimum Custodial Periods) Order 2024, to estimate automatic release dates:

• Standard Determinate Sentences (SDS): release at 40% of sentence now, moving to ⅓ from 1 October 2026 (section 23, Sentencing Act 2026)
• SDS+ (section 244ZA, Criminal Justice Act 2003): release at ⅔ now, moving to ½ from 1 October 2026. Youth detention under section 244ZA(6) stays at ⅔
• Excluded offences: offences in the Schedule to SI 2026/953 keep the release point they have now. That is ⅔ where section 244ZA applies, ½ for sexual, domestic abuse and national security offences and for Schedule 15 Part 1 offences of 4 years or more, and 40% otherwise
• Section 250 detention (under 18): release at ½, unchanged. Section 23(10) was not commenced for youth sentences (SI 2026/953, regulation 6)

People already in custody move to the new release point in ten stages by sentence length, running from 1 October 2026 to 8 June 2027. Anyone already released on a curfew licence is not reached until 12 October 2027.

We convert sentence lengths to days using the standard legal calendar:

Remand credit and added days are subtracted/added after the release fraction is applied.