5. Microsimulation Model Results: April 2025 to September 2025

The latest prison population projections are shown in Figure 16 and Table 2 below.

Figure 16. Prison population projections for April 2025 to September 2025. The projection range (sometimes referred to as the fan) 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.

As noted earlier, the Prisoners (Early Release) (Scotland) Act changed the release point for some offenders serving sentences of less than four years (short term prisoners) from 50% of their sentence to 40%. 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 were released in three tranches, commencing in February 2025. Thereafter, all eligible short-term prisoners are released at the 40% point of their sentence[1]. This change in release point is expected to lead to a sustained reduction in the short-term prisoner population, compared to what it would have been without the change in legislation[2]. The projections in this publication account for the ongoing reduction in the sentenced population, by adjusting release points accordingly.

The actual total prison population on 4th April was 8,138. The overall projected range for the average daily prison population in September 2025 is between 8,050 and 8,950. Modelling indicates it is likely that the overall prison population in Scotland will increase between the beginning of April 2025 and the end of September 2025.

The actual remand population on 4th April 2025 was 2,174. The overall projected range based on modelling for the average daily remand population in September 2025 is between 1,550 and 2,900. Modelling indicates it is likely that the remand prison population in Scotland will be at a similar level in September 2025 to what it was in April 2025. If the remand population decreases primarily because of enhanced monthly case conclusions, this could contribute to an increased sentenced population as people transition from remand to the sentenced population.

The actual sentenced population on 4th April 2025 was 5,964. The overall projected range based on modelling for the average daily sentenced population in September 2025 is between 5,950 and 6,650. Modelling indicates it is highly likely that the sentenced prison population in Scotland will increase between the beginning of April 2025 and the end of September 2025. The sentenced population is almost certain to rise if inflows exceed outflows. The rate of inflow to the sentenced population could increase if either the overall rate of transition from remand to the sentenced population increases, or if there is a greater inflow of individuals directly from the community to the sentenced population.

Table 2. Prison average daily population upper/lower estimates for April 2025 to September 2025[3]. These estimates are calculated from the 95% confidence intervals combined across all three scenario variants given in Table 1.

In Table 2 the upper total population and upper remand range estimates are from the scenario variant with a lower conclusion rate. The lower range estimates for the total and remand populations are from the scenario with a high conclusion rate.

It should be reiterated that whilst the projections are based on recent trends, they do not explicitly model the impact of potential future policy or operational changes and/or their potential impact on the prison population.