About this data

Source: Ministry of Justice, Criminal justice system statistics quarterly: December 2025

• Average custodial sentence length (ACSL) is the average length of determinate (fixed-length) prison sentences given to people sentenced to immediate custody in each year. It is the sentence the court gives, not the time actually spent in prison: most people are released part way through their sentence.
• Life sentences and sentences of imprisonment for public protection (IPP) have no fixed length, so are not included.
• From 2017, the Ministry of Justice processes court data differently, so figures before and after are not exactly comparable. Figures for 2010–2016 come from its detailed data tool.
• In the 12 months to June 2026, the average sentence for all offences was 20.5 months.

This chart appears in Prisons.