Why are prisons overcrowded?

“…About a quarter of the estate are living in a cell designed for one person with two people… that means that someone has to defecate where someone else eats their meal. They were designed for one person. There is an open toilet in that cell.”

– the then-Director General Chief Executive of HM Prison and Probation Service (HMPPS) describing overcrowded prison conditions to the Public Accounts Committee in January 2025.

Prisons in England and Wales are chronically overcrowded.

By the prison service’s own measure of safe and decent accommodation, there were fewer than 82,000 prison places in May 2026.

But the number of people in prison stood at almost 86,000, and official population projections indicate that it will continue to rise.

In recent years, the situation has become so severe that the Ministry of Justice (MoJ) has resorted to emergency measures to ease pressure on the system. These have included, under the previous government, an early release scheme under which some 13,325 people were released from prison between October 2023 and September 2024, and subsequently, a scheme to reduce temporarily the proportion of custodial sentences served in prison from 50% to 40% (“SDS40”). This scheme was described by the then Lord Chancellor and Secretary of State for Justice, Shabana Mahmood, as the only way to “avert disaster”.

In an attempt to steady the ship, the government has promised “radical reform” by means of the Sentencing Act 2026, which is intended to ensure that “prisons never run out of space again”. But the MoJ’s own impact assessment for the legislation admits that these “landmark” sentencing reforms will do nothing to address prison overcrowding, because any reduction in demand for prison places will be filled by an increasing prison population.  

The problems caused by overcrowding – from increasing violence and self-harm, to reducing the hope of rehabilitation and education – are well understood, but successive governments have lacked the political courage to deal properly with the issue. As Dame Anne Owers stated in her Independent Review of Prison Capacity in August 2025, “the 2022-24 prison capacity crisis was a conjunction of some specific circumstances. However, it was also a symptom of a systemic and long-running problem: the apparently irresistible pressure for more and longer prison sentences coming up against the immovable object of the difficulty, expense and overall effectiveness of building and running more prisons.

In response to the high level of interest, we have created a dedicated page on our website to explain what the problems are, how they arose, and how they might be solved.

Will we run out of prison space?

Technically, we have already; the prison system is being asked to accommodate more people than it was ever intended to hold.

Why, then, do we often see headlines claiming that the prison system is “almost full” or that there are only a few hundred “places left”? The answer lies in how prison population statistics are recorded and reported, which can lead to confusion.

The total number of people in prison is updated weekly in a regular statistical bulletin published by the MoJ. This bulletin tells us how many people are being held in men’s prisons and how many are in women’s prisons. It also provides comparative figures for the previous week and the previous year, so we can see if the population has risen or fallen.

But overcrowding data is published only once a month, when the MoJ releases a more detailed bulletin with population figures broken down for each prison in England and Wales. This is where it gets complicated…

For each prison, the MoJ publishes four figures:

Population. This is the number of people held in the prison.

Baseline Certified Normal Accommodation (CNA). This is the number of places in the prison, according to the prison service’s own measure of accommodation; as the MoJ puts it, “CNA represents the good, decent standard of accommodation that the service aspires to provide all prisoners”.

In-Use CNA. This is the baseline CNA figure, but without places that are not available for immediate use, such as cells that are damaged or affected by building works.

Operational Capacity. This figure, which is decided by prison group directors, is “the total number of prisoners that an establishment can hold taking into account control, security and the proper operation of the planned regime”.

When a prison’s operational capacity is higher than its CNA, it is usually the case that people are being made to share cells that are designed for one person. In some cases, three people will share cells designed for two.

Therefore, the Howard League analyses the scale of prison overcrowding each month, using the CNA figure for each prison.

But even these descriptions are a bit misleading: in some prisons, almost all prisoners are held in cells at what the MoJ calls their “maximum capacity”, and some of the cells that people are being crammed into are simply unfit for human habitation.

At the end of May 2026, more than half of the prisons in England and Wales were holding more people than their CNA. The most overcrowded jail was Wandsworth, which had a CNA of 1,430 but was being asked to accommodate 979. (Up-to-date population statistics for each prison can be found here.)

The prison system is beyond full. When politicians and journalists say that it is “almost full”, it is usually because they are quoting the operational capacity figure, which can be moved up or down at the discretion of senior prison officials.

Why does it matter if prisons are overcrowded?

When a prison is asked to accommodate more people than it is designed to hold, it piles more pressure on people working there and makes it harder to meet the needs of people living there.

If someone is sent to prison, we should do all that we can to help them to turn their life around and move on from crime. But overcrowding, coupled with chronic staff shortages, means that prisons cannot properly engage everyone in activities that help rehabilitation, such as exercise, education, employment and training. For many people, this means being locked in an overcrowded cell for 23 hours a day with nothing to do.

The growing tension behind bars is reflected in official statistics, which reveal worrying rises in self-harm and violence.

Prisons in England and Wales recorded more than 70,000 incidents of self-harm in 2025 – at a rate of one every seven minutes and twenty seconds. The Independent Advisory Panel on Deaths in Custody has noted that “prisons operating above capacity experience significantly higher rates of self-inflicted and natural deaths, particularly in Category B prisons” and that “while the prison population is expected to grow by 13% between 2025 and 2029, self-inflicted deaths are expected to rise by 21%, a disproportionately higher increase”. 

Manchester prison

Research undertaken by the MoJ has identified that prisoners in overcrowded cells are 19% more likely to be involved in an assault over a one-year period than those in non-overcrowded cells. It is perhaps unsurprising then that assaults rose to almost 31,545 in the year ending December 2025 – a rate of more than one every 17 minutes.  

Where incidents require police investigations or referrals to hospitals for treatment, they put further strain on local public services. 

Being stuck in an overcrowded cell for 23 hours a day with nothing to do is even harder in prisons where physical conditions are terrible. In October 2023, the MoJ confirmed that it had stopped all “non-essential maintenance work” because prisons were simply too crowded to allow for the closure of cells that such work would entail. We are not aware of this work yet restarting.

Worse still, official inspection reports reveal that people are being placed in cells that are not fit for purpose.

Section 14(2) of the Prison Act 1952 states that “no cell shall be used for the confinement of a prisoner unless it is certified by an inspector that its size, lighting, heating, ventilation and fittings are adequate for health and that it allows the prisoner to communicate at any time with a prison officer.“

Section 14(3) states that “a certificate given under this section in respect of any cell may limit the period for which a prisoner may be separately confined in the cell and the number of hours a day during which a prisoner may be employed therein.” 

As overcrowding pressures continue, however, it is becoming increasingly clear that cells are being certified as adequate when they are not.

In May 2024, we blogged about delays in constructing a new unit to replace the dark, damp and dilapidated cells in the segregation unit in Bedford prison, which inspectors branded a “disgrace”. Only after our intervention was the new segregation unit eventually opened in the autumn of 2024. The blogpost also mentions “crumbling infrastructure” in Lewes prison, a rat infestation in Pentonville prison, flies in Brinsford prison, and incidents in Winchester prison where men were able to dig through a wall using simple implements such as plastic cutlery.

Winchester prison

Several years later, similar issues continue to blight prisons across the country: the Independent Monitoring Board’s national annual report for 2025 described conditions in some prisons as “shocking”, with “dilapidated cells, flooding, extremes of temperature, infestations, and frequent large-scale equipment failures”. In Manchester prison, the IMB flagged “collapsed drains, sinkholes and a loss of water supply to half the prison for a week in November 2025”. In Albany prison on the Isle of Wight, there are still no in-cell toilets, with HM Inspectorate of Prisons reporting that people are “resorting to using buckets in their cells, the contents of which were often then tipped out of the windows.” At Bullingdon prison, the IMB reported three incidents involving spider bites between September and November 2025, with two prisoners requiring hospital treatment and one being warned “he could lose his leg”.

There remains a maintenance backlog of over £1.8 billion, without even taking into account essential fire safety improvement works to ensure that prisons are compliant with fire safety regulations. The MoJ itself estimated in 2024 that it would cost £2.8 billon over the next five years to bring the whole estate into a ‘fair’ condition, which was more than double its budgeted maintenance expenditure. Without a change in approach, it is impossible to imagine that reports from HMIP and the IMB on prison conditions will be materially different in the future.

How did we get into this mess?

These problems did not come out of the blue. In 2014, we published a briefing called Breaking Point, which revealed that 78 prisons were holding more people than they were designed to accommodate. We wrote: “Urgent action is needed to ease the strain on the prison system. The MoJ must take action to reduce the prison population and increase prison officer numbers.”

The prison population has almost doubled in the last 30 years. After a rapid increase in the 1990s and 2000s, it began to stabilise in the 2010s and decreased slightly during the Covid-19 pandemic, but it has since risen again to reach record heights.

This is not a response to rising crime – in fact, recorded crime has fallen – but a sign of how changes in sentencing policy, led by politicians, have had a dramatic impact. Prison sentences have been handed down more and more, and they have got longer and longer over time.

Campaigns calling for the creation of new offences, or the introduction of longer sentences, to address specific issues or problems have contributed to this shift. The impact of these campaigns can be far-reaching – when politicians make sentences longer for one crime, it often leads to calls for longer sentences for other crimes. And so it goes on.

A backlog of cases in the courts, which grew longer during the Covid-19 pandemic, has not helped. The number of people in prison on remand – awaiting trial or sentence – reached its highest level for at least 50 years in 2025.

Meanwhile, the number of people who have been recalled to prison after being released also reached a record high in 2025. Prisons overwhelmed by overcrowding are not preparing people for life outside, and there is insufficient support for people when they are released. Too often, we see people leaving prison without somewhere to live.

Why don’t we just build more prisons?

Despite the current government acknowledging in that “we cannot build our way out of the chaos”, it is nonetheless attempting “the biggest prison expansion since the Victorian era”.

But when the prison system gets bigger, the problems within it get bigger, becoming harder to solve. And it makes no sense to build new jails when there are too few staff to run the ones we already have.

Many stories about the prison system focus on the failings in jails built during the Victorian era, but official inspection reports reveal that there are challenges in newer ones as well.

A January 2024 inspection of Five Wells prison discovered that almost 750 officers had been hired since it opened in 2022, but only 272 remained in post.

In February 2024, inspectors noticed “slow but perceptible decline” in Buckley Hall prison, which opened during the 1990s.

Lowdham Grange prison, which opened in 1998, was found to be so unsafe in May 2023 that the government had to take over the running of it. HMIP’s March 2025 inspection found that use of force incidents had trebled, violent incidents had increased, and the rate of self-harm was the third highest among category B training prisons. There had been 10 deaths in custody since the 2023 inspection. 

Problems in prisons spill out into the towns and cities around them, and new jails put added strain on local public services. It should surprise no one that proposals to build more prisons have met significant opposition from residents living nearby.

What should we do instead?

Emergency measures helped to alleviate the immediate crisis in capacity and changes in the Sentencing Act – including a new presumption against the imposition of short sentences, and a new release model that will see many people released at a third of the way through their sentence – will buy some more time.  

But none of the forecasted changes will address the fact that we have one of the largest prison populations in Western Europe and it is projected to continue to rise, outstripping prison capacity again in a matter of years.  

At the root of this lies the uncomfortable truth that, until politicians grasp the nettle of sentence inflation, the prison system will remain chronically overcrowded, staggering from foreseeable capacity crisis to foreseeable capacity crisis.  

For too long, criminal justice policies have been judged on whether they appear “tough” or “soft”, when what really matters is whether they work. We can start to put things right if we shift our focus from punishment to problem-solving. If someone needs support to move away from crime, they will have better access to the services that can help them if they are being supervised in the community than if they are locked in a prison cell for hours on end with nothing to do.

Making sentences longer and longer puts intolerable pressure on the prison system and creates bigger challenges that will have to be tackled sooner or later. Dealing with the consequences takes valuable resources away from preventing crime and supporting victims.

Common sense tells us that someone is much less likely to be involved in crime if they have a settled home and steady employment. Imagine what we could achieve if we stopped building prisons and invested in homes, schools, hospitals and jobs instead.

Want to know more about the prisons crisis? Read our explainer on sentence inflation.