In this guide
- What is a fair usage policy?
- Which networks have fair usage policies on unlimited data?
- What counts as excessive data usage?
- Can I tether with an unlimited data SIM?
- Does unlimited data include roaming?
- Do I need unlimited data?
- FAQs
- Will my data actually stop if I exceed the fair usage limit?
- Are fair usage limits applied automatically?
- Where can I compare unlimited data deals?
- Editorial policy
Most unlimited data plans in the UK are genuinely unlimited in the sense that your data will not cut off or incur extra charges when you use a lot. However, networks can apply fair usage policies that allow them to reduce your speeds if your usage is considered excessive. This guide explains how fair usage policies work, which networks apply them, and what the limits are.
Reviewed by Phil Brown, founder of SIM Only Finder. Before launching SIM Only Finder, Phil worked in UK mobile retail at Three UK, advising customers on SIM plans, contracts, and network choices. He has spent over a decade running consumer comparison platforms. About the author
Last reviewed: March 2026.
What is a fair usage policy?
A fair usage policy (FUP) sets a threshold for what a network considers reasonable monthly data consumption. If you exceed that threshold, the network may reduce your connection speeds for the rest of the billing period. Your data does not stop working, but it may become noticeably slower.
Fair usage policies are permitted under Ofcom rules, provided they are clearly stated in a network's terms and conditions and are reasonable in their application. They are primarily aimed at preventing a small number of users from consuming extremely large volumes of data in ways that affect network performance for everyone else. For the vast majority of users, fair usage thresholds are high enough that they will never come close to triggering them.
Which networks have fair usage policies on unlimited data?
The following networks apply a fair usage threshold on their unlimited data plans. Always check the current terms on the network's website before signing up as these figures can change:
- EE: 600GB per month. Exceeding this twice within six months may result in speed restrictions or a transfer to a different plan.
- Giffgaff: 650GB per month. Exceeding this twice within six months may result in speed restrictions or additional charges.
- Honest Mobile: speeds reduced to 3G if you use over 650GB in a billing cycle.
- O2: 650GB per month. Exceeding this twice within six months may result in speed restrictions or a transfer to a different plan.
- Tesco Mobile: no specific data cap stated, but excessive use that affects other customers may result in a warning, speed restrictions, or suspension.
- Lycamobile: 450GB per month. Exceeding this twice within six months may result in speed restrictions.
- Vodafone: 600GB per month. Exceeding this twice within six months may result in investigation and possible transfer to a different plan.
For networks running on the VodafoneThree network (including Smarty, iD Mobile, Talkmobile, Voxi, and Asda Mobile), post-merger terms are still being updated. Check the current terms with each network directly before signing up.
The following networks do not currently state a specific fair usage threshold on their unlimited data plans:
- Asda Mobile
- iD Mobile
- Lebara
- Sky Mobile
- Smarty
- Talkmobile
- Three: no stated fair usage policy on unlimited data plans. Three continues to sell plans under its own brand following the completion of its merger with Vodafone in June 2025.
- Voxi
Note that even networks without a stated threshold reserve the right to take action against usage they consider abusive or that negatively affects the network for other customers.
What counts as excessive data usage?
Fair usage policies are generally aimed at preventing a small minority of users from using a mobile unlimited plan as a home broadband substitute or running data-intensive servers. Streaming video, browsing, video calls, social media, and general everyday smartphone use will not come close to triggering fair usage thresholds on any UK network. The thresholds are set at hundreds of gigabytes per month precisely because they are not meant to affect normal usage.
Can I tether with an unlimited data SIM?
Yes. Tethering (using your phone as a mobile hotspot to share your data connection with a laptop, tablet, or other device) is permitted across all the major UK networks covered in this guide, including EE, O2, Vodafone, Three, iD Mobile, Smarty, Voxi, Giffgaff, Tesco Mobile, Sky Mobile, Lycamobile, Lebara, Talkmobile, and Asda Mobile. There are no longer separate tethering charges or additional allowances required. Data used while tethering comes from the same pool as everything else on your plan.
That said, tethering is the activity most likely to push your usage toward a fair usage threshold. Streaming video, downloading large files, or running video calls through a tethered laptop will consume significantly more data than typical smartphone use. Networks that publish a specific threshold, such as EE at 600GB per month or Giffgaff at 650GB per month, apply those limits to all data use including tethering. Networks without a published threshold still reserve the right to act on usage they consider excessive or that negatively affects other customers.
All plans are for personal use only. Using a SIM as a permanent fixed broadband substitute, particularly in a router that runs continuously, sits in a grey area on most networks and is worth checking against your specific network's terms before doing so.
Does unlimited data include roaming?
No. Unlimited data plans cover your domestic UK usage. When you travel abroad, your data usage is subject to separate roaming allowances and fair use limits, which are set independently from your UK plan.
Most UK networks include EU roaming on their plans, but cap the amount of data you can use abroad each month. This cap is separate from your domestic unlimited allowance. For example, a network might include 12GB of roaming data in the EU even if your domestic plan is unlimited. Check the specific terms of the plan you are considering before travelling. For more detail on how roaming works, see our guide to EU roaming fees.
Do I need unlimited data?
According to Ofcom's Connected Nations report, the average UK mobile user consumes around 10.6GB of data per month. If your usage is around this level or below, an unlimited plan is unlikely to represent the best value. A capped plan at a lower monthly cost will often work out cheaper overall.
Unlimited data makes sense if you regularly stream video on mobile, use your phone as a hotspot for other devices, or work remotely without consistent Wi-Fi access. You can compare current unlimited data SIM-only deals on our deals page, where results are sorted by monthly cost.
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FAQs
Will my data actually stop if I exceed the fair usage limit?
No. Exceeding a fair usage threshold typically results in reduced speeds for the remainder of your billing period, not a complete cut-off. Your data continues to work, but may feel noticeably slower for heavy tasks like video streaming.
Are fair usage limits applied automatically?
Yes. Speed reductions are applied automatically by the network once the threshold is crossed. You do not usually receive a warning in advance, though your network may contact you if you exceed the limit repeatedly.
Where can I compare unlimited data deals?
You can compare all current unlimited data SIM-only deals on our deals page, sorted by monthly cost and filterable by network.
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