Metric permalink
Prison capacity utilisation (E&W)
Part of the Rule of Law and Safety domain. Prison population as a percentage of usable operational capacity in England and Wales, measuring the margin of safety in the custodial estate.
Latest data
Latest reading
10 Aug 2026
A higher reading is treated as worse for this indicator.
Score composition
Stress score
Blended from three components: (60% weight), trend (30% weight) and volatility (10% weight). Full formula on the methodology page.
Level · 60% weight
Bounds: scored against fixed best/worst limits, used until a metric has about eight years of verified data to rank against.
Trend · 30% weight
Measured from the direction and size of the change between the two most recent readings.
Volatility · 10% weight
9Measured from how much this indicator has swung period on period across its recorded history.
Data confidence and provenance
Confidence and source
How much weight to put on the reading, the mean data-confidence across the component metrics (source quality, recency and completeness).
Source
Prison population weekly/monthly statistics
- Update frequency
- Weekly
- Reliability
- high
Provenance
- Provider
- Ministry of Justice
- Series ID
- prison population vs usable operational capacity, E&W
- Frequency
- periodic
- Accessed
- 13 August 2026
Known weakness
Usable operational capacity is a managed administrative figure that can be adjusted by HMPPS; capacity reductions (e.g. cell refurbishments) can mechanically worsen the ratio.
Notes
Verified official value from Ministry of Justice (prison population vs usable operational capacity, E&W), accessed 2026-08-13.
Historical values
History
| Period | Value | Relative |
|---|---|---|
| 2025 | 97.8 | |
| Jun 2026 | 96.2 | |
| Jul 2026 | 96.4 | |
| 3 Aug 2026 | 97.3 | |
| 10 Aug 2026 | 97.4 |