1. Executive Summary

This is the seventh report published since June 2023 on the Scottish Government modelling of the level of demand for prison accommodation in Scotland. It presents prison population projections for the six-month period from April to September 2025[1]. They have been produced using ‘microsimulation’ scenario modelling, which simulates prison arrivals and departures, to estimate the number of individuals in prison on a particular date in the future.

The projections are produced to help inform high level decision making, planning and policy development. As they do not take account of the complexity of the prison population, they are not intended for use in the day-to-day management of those in prison.

Developments since the last projections publication

The projections were last published in December 2024. Legislation to help reduce the prison population was passed by the Scottish Parliament on 26th November 2024 and became the Prisoners (Early Release) (Scotland) Act on 22nd January 2025[2]. The Act changed the release point for some offenders serving sentences of less than four years (short term prisoners) from 50% to 40% of their sentence. There was no change to the release point for prisoners serving sentences for domestic abuse or sexual offences, who continue to be released at 50%. Those immediately impacted by the change were released in three tranches between February and late March 2025. After which point, all eligible short-term prisoners are released after serving 40% of their sentence[3]. The measures are expected to lead to a sustained reduction in the short term prisoner population, compared to what it would have been without implementing the legislation[4]. The population projections presented in this publication account for the ongoing reduction in the sentenced population, by adjusting release points accordingly. Three scenarios have been modelled with various assumptions about case conclusion rates (central, high, and low).

As highlighted in previous publications, the key factors for the prison population in the short term are expected to be flows into and out of the remand and sentenced populations.

Key Points

On 4th April 2025, the overall prison population in Scotland was 8,138, and the remand and sentenced populations were 2,174 and 5,964, respectively. The latest prison population projection modelling (shown in Figure 1) indicates:

• It is likely[5] that the overall prison population will increase between 1st April 2025 and 30th September 2025. It is projected that the average daily prison population could be between 8,050 and 8,950[6] in September 2025.

• It is likely that the remand population will be at a similar level in September 2025 to what it was in April 2025. It is projected that the average daily remand population could be between 1,550 and 2,900 in September 2025.

• It is highly likely that the sentenced population will increase between April 2025 and September 2025. The average daily sentenced population could be between 5,950 and 6,650 in September 2025.

• Between November 2024 and February 2025[7], the actual prison population tended to align with the projected level of the central scenario of the last set of projections[8]. If this were to hold in the latest projected period, then it is likely that the demand for prison spaces will rise between April and September 2025.

• However, it is worth noting that in some past growth periods (e.g. early 2023 and early 2024) the actual population tended to track the top end of the projection range for a number of weeks.

• Over the coming months remand arrivals, sentenced arrivals and case conclusion levels will be monitored to assess with which scenarios the actual prison population level is most closely aligned.

Figure 1. Prison population projections for April 2025 to September 2025. The projection range includes the overlapping 50%, 75% and 95% confidence intervals for all scenario variants given in Table 1. The actual population is shown as a series of black points.