UK Prison Capacity & Early-Release Policy Simulator

Policy Intervention Levers Counterfactual Lab

Scenario Presets

SDS Release Threshold 40% of Sentence

Recall Supervision Reform 15% Churn Reduction

Remand Inflow Share

New Prison Places Delivery 3,200 places/yr

Monthly Total Custodial Inflow 4,320 / month

Source Grounding: Models standard determinate sentences (SDS) early eligibility, license recalls churn under probation supervision, court backlog remand velocity, and modular cell construction pipelines.

Initial Headroom

1,450

Buffer: 1,450 floor

Monthly Net Delta

-185

With active reform

12-Mo Projected Pop

86,150

From 87,450 baseline

Annual Cell Gain

3,200

Commissioned places

24-Month Custodial Population vs Usable Capacity Projection Model (Sept 2026 - Aug 2028)

Monthly Custodial Cohort Balance Sheet Flow Accounting Breakdown

Cohort Stream	Baseline Flow	Policy Impact	Effective Monthly Volume