Report
Illegal online gambling: Challenges of estimating the size of the illegal gambling market
The final chapter of the Gambling Commission's research into the illegal online market, focusing on challenges estimating the size of the market.
Introduction and context
Key point summary
Key points in this section are as follows:
- this report builds on our previously published approach to estimating trends of consumer engagement with illegal gambling websites. We have explored how we can develop this work further to make an estimate of the overall size of this market – in terms of consumer expenditure – or the Gross Gambling Yield (GGY) - associated with it
- estimating amounts of illegal activity in any sector is a significant challenge, due to its nature. We have sought to take a realistic, informed approach – this means we are clear about the limitations of available data and the uncertainty of estimates we can make
- we are not yet ready to publish an estimate. In this report we explain the reasons for this and opportunities to work towards this goal. Understanding the size of this market is important – but we will only publish an estimate that we judge to be credible and fit for public use
This report discusses the work we have undertaken to explore the size of the illegal gambling market in Great Britain. We highlight different methodologies that can be applied and examine the challenges of making robust and reliable estimates for an activity which is largely hidden and for which available data is limited.
We will never know the exact amount that is being spent within the illegal market. That said, although a definitive estimate of the size of this market is currently out of reach, it is a realistic goal to work towards and we will publish our findings when they are ready. In this report we set out the factors that make a definitive estimate difficult and explain the actions which can be taken to overcome these.
The Gambling Commission, as a public body, can only publish data that we see as robust and reliable. We follow the principles and approach set out in the Government’s AQuA Book1. In particular, we have sought to be clear about the uncertainty associated with estimates and have been transparent about the methodologies used and limitations involved. We will only publish data when we assess it as suitably reliable and fit for public use.
We look forward to working with academia, operators, other regulators and stakeholders to make progress towards this goal.
Why estimate the size of the illegal gambling market
The Gambling Commission has a strategic objective of making it difficult for illegal gambling to be offered at scale to consumers in Great Britain. This is a priority as this market poses a risk to members of the public and damages legitimate businesses.
The benefits of being able to estimate the size of this market include:
- helping us to understand the scale of risk posed to consumers and the public – so we can allocate existing resources proportionately and further demonstrate the case for wider action by stakeholders who can play a role in tackling this problem
- helping us to further understand the overall impact of our disruption work – building on the progress already made on monitoring trends in engagement and the impact of disruption on specific sites
- allowing us to work internationally with other regulators to develop and deploy robust methodologies which will allow us to benchmark Great Britain with other jurisdictions.
Context
This report is the fourth report in our series of publications on illegal gambling.
Publication 1 – Illegal online gambling: Consumer awareness, drivers and motivations explored the factors that motivate consumers to use illegal sites – and the extent that they understand if they are using a regulated operator. One of the key messages from this analysis, based on engagement with many consumers, was that motivations are varied and cannot be explained by a single factor.
Publication 2 – Illegal online gambling: Consumer engagement and trends focused on trends in consumers engagement with illegal sites. A large number of illegal websites exist and are used by consumers. Analysis of trends, however, showed no evidence of persistent growth in their use. More work is needed to explore of fluctuations observed are seasonal variations, or part of a longer-term trend.
Publication 3 – Illegal online gambling: Disruption of illegal online gambling highlighted how we disrupt illegal websites and how we are continuing to strengthen our approach to enforcement. This report also illustrated how we can measure the impact of disruption activity on illegal websites.
Scope of this report
We define illegal gambling as the facilitation of commercial gambling to consumers in Great Britain without an operating licence from the Gambling Commission or a valid exemption for non-commercial gambling. This applies regardless of where in the world the gambling is provided from. A gambling licence issued in another country does not permit a company to provide gambling to consumers in Great Britain. The illegal online market is characterised by a complex interplay of operators, affiliates, payment methods, and access channels. Since the illegal market is not subject to our regulation and the safeguarding this provides, there is a high rate of change as new technologies and products emerge.
In Illegal online gambling: Consumer engagement and trends we set out the scope of our data collection in more detail. The key points to note include:
- we recognise that illegal land-based gambling is also a risk to the licensing objectives– however, our focus for this report has been the online sector as there is more potential to access data to estimate the scale of this aspect of the market
- any illegal gambling websites will look similar or identical to legal sites - many consumers may be using them without knowing they are not licensed by the Gambling Commission
- access to illegal sites will also be facilitated by use of Virtual Private Networks (VPNs) – this is discussed in report 2 and included in our estimate of engagement trends
- use of crypto casinos is a notable feature of many of the illegal websites we have identified. These often appear alongside more traditional gambling products
- illegal gambling can also be facilitated directly within Social Media Apps, such as Telegram. At present, we have not identified a methodology that would accurately capture this activity.
Structure of this report
This report is structured as follows:
- the Methodology section outlines strengths and weaknesses of methodology options
- the Dwell-time approach section – Focuses on the ‘dwell-time’ methodology – outlining the challenges of making accurate estimates and opportunities to develop this approach
- the Channelisation rate approach section sets out a similar analysis of ‘channelisation’ based methodologies
- the final part provides a discussion on conclusions and next steps.
References
1 The AQuA Book (opens in new tab), Government Operational Research Service, Government Analysis Function, Government Actuary’s Department, Office for National Statistics, July 2025.
Executive summary - Challenges of estimating the size of the illegal gambling market Next section
Comparisons of different methodologies - Challenges of estimating the size of the illegal gambling market
Last updated: 6 November 2025
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