Best SIM-Only Deals for Heavy Data Users UK 2026

If you regularly stream video, use your phone as a hotspot, or burn through more than 50GB a month on mobile data, a standard SIM plan is going to cost you a fortune — or leave you throttled before the month is out. Heavy data users need deals built around proper high capacity: 100GB minimum, or genuine unlimited with no hidden speed caps. This guide cuts through the marketing and tells you exactly which SIM-only deals are worth it for people who actually use a lot of data, with current July 2026 prices, honest notes on throttling, and a breakdown of which networks let you hotspot freely.

All prices are as of July 2026. Before committing, it is worth checking whether SIM-only makes financial sense for you — our guide to SIM-only vs phone contracts runs the full maths. For deals across all data tiers including budget plans, see the best SIM-only deals UK guide.

Quick comparison: best high-data SIM deals July 2026

Here is the at-a-glance view. Scroll down for the full breakdown of each plan, including throttling policies and hotspot limits.

Provider	Plan	Monthly	Contract	Network	Hotspot	Price rises?
iD Mobile	Unlimited	~£16/mo	30-day rolling	Three	Yes, unlimited	No
Three	Unlimited	~£16/mo	12-month	Three (direct)	Yes, unlimited	Yes
Lebara	Unlimited	~£22.50/mo	12-month	Vodafone	Yes	No
EE	Unlimited	Check ee.co.uk	30-day / 24-month	EE	Yes	Yes
O2	Unlimited	from ~£22/mo	Various	O2	Yes	Yes
VOXI	60GB (3x offer)	~£10/mo	30-day rolling	Vodafone	Yes	No
VOXI	140GB + unlimited social	~£15/mo	30-day rolling	Vodafone	Yes	No
O2	100GB	~£16/mo	12-month	O2	Yes	Yes
Lebara	50GB	~£15/mo	30-day rolling	Vodafone	Yes	No

Quick verdict cards

Best unlimited SIM deals UK 2026

Unlimited data is the right call if you regularly use more than 80–100GB a month, use your phone as a hotspot, or simply do not want to think about data limits. Here are the best options, ranked by value for heavy users.

iD Mobile Unlimited — ~£16–£18/mo (30-day rolling)

iD Mobile is the strongest all-round pick for heavy data users. At ~£16/mo on a 30-day rolling contract (as of July 2026, source: iD Mobile / Uswitch), you get genuinely unlimited data on Three’s network — the UK’s fastest average 5G at roughly 210 Mbps. There is no separate cap on tethering or hotspot use: the full unlimited data works for personal hotspot as well as on-device use. iD Mobile also has a data rollover feature that carries unused data forward to the following month, though on unlimited that is less relevant. No mid-contract price rises. Roaming included in 50 destinations.

There is also a 12-month option that often comes with a gift card promotion, bringing the effective monthly cost lower — check iD Mobile’s site for the current offer as these promotions change regularly. If you want maximum flexibility and the same unlimited package, the 30-day rolling plan at ~£16–18/mo is the one to pick. The only practical trade-off versus taking a direct Three contract: during very high network congestion, MVNO customers may sit slightly behind direct Three customers in priority order. In practice, this is rarely noticeable.

Check iD Mobile’s website for current unlimited plan pricing and any active gift card promotions — prices update regularly.

Three Unlimited — from ~£16/mo (12-month)

If you would rather deal directly with Three than an MVNO, Three’s own unlimited SIM starts from ~£16/mo on a 12-month contract (as of July 2026, source: Three / Uswitch). You get the same fast 5G network with no throttling for personal use, and as a direct customer you have the highest network priority during congestion. Three’s roaming is strong — 70+ destinations on most plans. The genuine downside: Three applies mid-contract price rises of £1.80–£2.30/mo (since February 2026), which adds up over a 12-month commitment. If price stability matters to you, the iD Mobile MVNO route on the same network avoids this entirely.

Three’s unlimited is genuinely unlimited — no fair-use cap of the kind that some other networks quietly apply at 300GB or 600GB. For users who burn through very high volumes or run heavy tethering sessions, Three direct is worth considering alongside iD Mobile.

Check Three’s website for current unlimited SIM plans and any promotional rates.

EE Unlimited — best UK coverage

EE is consistently rated the UK’s best network for coverage, particularly outside cities. If you live or work in a rural area where Three and Vodafone can struggle, EE’s unlimited SIM is worth the premium. EE’s unlimited plans come with 5G+ and EU roaming, and the network quality in patchy areas is meaningfully better than the competition (source: Ofcom Connected Nations Report 2026). Check ee.co.uk for current pricing — EE updates its SIM-only deals regularly and often runs promotional discounts from the standard rate. One important caveat: EE applies an annual price rise of £2.50/mo (for plans taken from July 2025 onwards), and EE’s unlimited plans have a 600GB fair-use threshold beyond which speeds may be reduced in congested areas — an unusually high bar that very few users will hit, but worth knowing.

Lebara Unlimited — ~£22.50/mo (12-month) or ~£24.95/mo (rolling)

Lebara’s unlimited plan is a solid choice for heavy data users who also make international calls — Lebara includes minutes to 50+ countries as standard in all plans. On Vodafone’s network, you get 5G where available and broad UK coverage. The 12-month unlimited plan sits at ~£22.50/mo and the 30-day rolling version is ~£24.95/mo (as of July 2026, source: Lebara). No mid-contract price rises — Lebara has not raised prices since 2020, which is a genuine standout in the current market. EU roaming and data are included. If you regularly call family or colleagues abroad, Lebara’s international minutes make it a dual-purpose pick.

For pure UK unlimited without the international angle, iD Mobile and Three are cheaper. But if international calls matter, Lebara’s pricing stacks up well — you would pay significantly more adding international minutes as an add-on from the big four. Lebara also requires no credit check, which matters if you are newer to the UK or have a thin credit file.

Best high-data SIM deals without going unlimited

Not everyone who uses a lot of data needs true unlimited. If your monthly usage consistently lands between 50GB and 100GB, a defined high-data plan is often cheaper than unlimited — and you avoid paying for a theoretical ceiling you will never hit.

VOXI 60GB (3x data offer) — ~£10/mo (rolling)

VOXI is currently running a 3x data promotion on its £10/mo plan — which means you get 60GB instead of the standard 20GB (promotion valid to 30 September 2026, as of July 2026, source: VOXI). On Vodafone’s network with 5G included, this is outstanding value for a 30-day rolling plan. VOXI also includes unlimited social media data — Facebook, Instagram, WhatsApp, TikTok, Snapchat, and X — that does not count against your 60GB allowance, which extends its practical value further. No mid-contract price rises. VOXI’s £15/mo plan gets you 140GB plus unlimited social media, music, and video streaming — a step up for heavier users.

The 3x data promotion is time-limited. Check VOXI’s website for the current data allocation on each plan — if the promotion has ended by the time you read this, the standard 20GB plan at £10/mo is considerably less competitive.

Check VOXI’s website for current data allocations — the 3x data promotion ends 30 September 2026.

O2 100GB — ~£16/mo (12-month)

O2’s 12-month SIM plan at ~£16/mo gives you 100GB of data — a defined high allowance that suits users who know roughly how much they use and do not want to commit to unlimited. Every O2 plan includes unlimited calls and texts plus access to O2 Priority, O2’s perks scheme offering regular freebies, early-access event tickets, and retail discounts. O2’s network runs across 98% of the UK population for 4G, and 5G coverage is expanding steadily. Hotspot and tethering are included (as of July 2026, source: O2). The catch: O2 applies an annual price rise of up to £2.50/mo each April — so factor a potential rise into your total cost over a 12-month term.

Lebara 50GB — ~£15/mo (30-day rolling)

If you want a defined 50GB allowance without committing to unlimited — and you make international calls — Lebara’s 50GB rolling plan at ~£15/mo is worth a look (as of July 2026, source: Lebara). As with all Lebara plans, calls to 50+ countries are included at no extra cost, no credit check is required, and there are no mid-contract price rises. Runs on Vodafone. This plan sits at the boundary of heavy and moderate data use — if you regularly push past 50GB, the Lebara Unlimited at ~£22.50/mo on a 12-month contract makes more sense per gigabyte.

Do “unlimited” SIM plans throttle your speed in the UK?

The honest answer is: it depends on the network and the plan. “Unlimited” is not always the same thing from provider to provider, and the difference matters for heavy users.

Three and iD Mobile are the most genuinely unlimited. For personal use — on-device data and tethering — there is no fair-use cap and no speed reduction based on how much you have used in a month. You can use 300GB, 500GB, or more, and Three will not slow you down (for personal use — commercial or resale use of unlimited is a different matter and against the terms).

EE applies a 600GB fair-use threshold. If you consume more than 600GB in a month, EE may reduce your speeds at busy locations. In practice, almost no mobile user will hit 600GB in a month of personal use — this is effectively unlimited for all real-world purposes.

O2 and Vodafone have varying fair-use policies depending on the specific plan. Check the plan terms on their websites before signing up, as the thresholds can differ between plan tiers.

Network congestion management is separate from fair-use throttling — all networks may slow speeds during peak times in busy locations regardless of your plan. This applies to everyone, not just unlimited users. The practical difference you will notice between unlimited plans is mostly network quality in your area, not throttling.

Which SIM-only deal is right for you?

If you stream video and use social media heavily

Go unlimited. Streaming HD video uses roughly 3GB per hour. At that rate, 100GB is exhausted in around 33 hours of streaming — about one hour a day. If you stream on your commute, during lunch, and in the evenings, unlimited is the only plan that makes sense. iD Mobile at ~£16/mo on a 30-day rolling plan is the best starting point. If VOXI’s 3x promotion is still running, its £15/mo plan with unlimited video streaming included is worth comparing head-to-head.

If you rely on your phone as a hotspot

You need unlimited data on a network that allows full tethering without a separate hotspot cap. iD Mobile and Three both fit this profile. EE’s unlimited plan also allows hotspot use, though the total monthly data is subject to the 600GB FUP. Avoid plans that cap hotspot at a lower amount than your total data — some lower-tier plans from direct networks do this, though the unlimited plans reviewed here do not.

If you want high data without paying for unlimited

If your typical monthly usage is 50–80GB, a defined high-data plan can save you money versus unlimited. VOXI’s 3x promotional offer at ~£10/mo (60GB, valid to September 2026) is the standout pick if it is still running. O2 at ~£16/mo for 100GB on a 12-month contract is solid, though at that price iD Mobile Unlimited is worth a direct comparison. Lebara’s 50GB plan at ~£15/mo is the pick if international calls are part of your usage.

If you travel frequently in Europe

Check roaming carefully before committing. iD Mobile includes a 30GB roaming allowance across 50 destinations. Three direct includes roaming in 70+ destinations. EE includes EU roaming across most plans. Lebara includes EU roaming and India roaming — useful if you travel between the UK and South Asia. VOXI includes EU roaming but check the data cap that applies while abroad, as it may differ from your UK allowance.

How to switch to SIM-only and keep your number

Keeping your existing mobile number when switching networks is straightforward in the UK. The process is regulated by Ofcom and takes one working day once the PAC code is activated.

1. Check your current contract end date — text PAC to 65075 (free, works on any UK network). You will receive your PAC code and contract end date by text within 60 seconds.
2. Compare plans and sign up — order your new SIM from the provider of your choice. Most SIMs arrive within 1–3 days. Do not cancel your existing contract yet.
3. Give the PAC code to your new provider — do this online or by phone when activating your new SIM. The switch will happen on the next working day.
4. Keep your old SIM active until the switch completes — calls and texts will transfer automatically. You do not need to do anything on switchover day.
5. Cancel your old contract — once your number has transferred and your new SIM is working, contact your old network to confirm cancellation. Any final bill will be calculated to the date of the PAC transfer.

If you do not need to keep your number, you can skip the PAC step entirely — just insert the new SIM and activate it on the new network.

Frequently asked questions

What counts as “heavy data use” on a mobile SIM?

There is no official definition, but in practical terms: if you use more than 30GB a month you are in the higher-usage bracket, and above 80–100GB you are a heavy user. Streaming 1 hour of HD video uses roughly 3GB; a 4K stream uses around 7GB per hour. Regular hotspot use — sharing your mobile data with a laptop — can add 10–30GB or more per month depending on what you are doing on the connected device. If you work from your phone as a hotspot or commute with a streaming habit, 100GB+ plans or unlimited are the practical options.

Do unlimited SIM deals actually throttle your speed in the UK?

Most genuine unlimited plans from Three, iD Mobile, and EE do not throttle speeds based on how much data you have used that month. Three and iD Mobile have no fair-use cap for personal use. EE applies a 600GB monthly fair-use threshold — speeds may be reduced at busy locations beyond that point, but almost no personal user will reach 600GB in a month. All networks may manage speeds during peak congestion (typically evenings in city centres), but this applies to all customers, not just heavy users. Always check the specific terms for the plan you are buying, as conditions vary between plan tiers.

Can you use an unlimited SIM as a home broadband replacement?

Technically yes, but with caveats. iD Mobile, Three, EE, and O2 unlimited plans all allow hotspot use, so you can share mobile data with your home devices via your phone’s personal hotspot. In practice, mobile connections can be less consistent than fixed broadband — speeds vary by time of day, location, and how many people are on the mast. For a single person or couple with moderate usage, an unlimited SIM can substitute for home broadband in a pinch. For a household with multiple people streaming simultaneously, fixed-line broadband will generally be faster and more stable. See our broadband provider guide if you need a home connection as well.

Which network has the fastest 5G for heavy data users?

Three consistently tops UK 5G speed tests, with an average 5G download speed of around 210 Mbps (source: RootMetrics 2026 data). iD Mobile runs on Three’s network and delivers the same speeds. EE comes second for average 5G speeds but leads on coverage — particularly outside cities and in rural areas. Vodafone’s 5G speeds are improving but trail Three and EE on average download performance. O2’s 5G network is expanding but average speeds are currently below Three and EE. For pure download speed, Three or iD Mobile is the answer. For reliable coverage in rural areas, EE wins.

Is there a difference between iD Mobile and Three if they use the same network?

Both use Three’s masts and deliver the same 5G speeds in most situations. The main practical differences are: (1) Priority — during peak network congestion, Three’s own customers may have slightly higher priority than iD Mobile MVNO traffic, though this is rarely noticeable in practice; (2) Price rises — Three applies mid-contract price rises of £1.80–£2.30/mo (since February 2026), while iD Mobile does not; (3) Roaming — iD Mobile offers 30GB roaming in 50 destinations, while Three’s own plans cover 70+ destinations with a higher roaming allowance; (4) Customer service — direct Three customers have access to Three’s own support channels, while iD Mobile has its own (generally well-rated) service. For most users, iD Mobile is the better financial choice due to no price rises.

How do I switch SIM-only and keep my existing number?

Text PAC to 65075 (free on any UK network). You will receive your PAC code and contract end date by return text within 60 seconds. Then sign up with your new provider, give them the PAC code when activating your SIM, and your number will transfer on the next working day. Keep your old SIM active until the transfer completes — do not cancel your old contract before this. Once the new SIM is live with your number, contact your old network to close the account. The whole process takes one working day from giving your new provider the PAC code.

Which unlimited SIM deal is best for travelling in Europe?

Three (direct) includes roaming in 70+ destinations — the broadest footprint. iD Mobile includes a 30GB EU roaming allowance in 50 destinations. EE includes EU roaming across its unlimited plans. Lebara includes EU roaming and India roaming on all plans. VOXI includes EU roaming but the data you can use abroad may be capped at a lower amount than your UK allowance — check the current terms before buying. If Europe travel is a regular part of your usage, Three or iD Mobile offer the most destinations, while Lebara is the pick if India is on your list.

Prices and deals are checked before publication and marked with their source date. Mobile SIM pricing changes frequently — always verify the current rate at the provider’s website before signing up. TheTechVector earns a commission from some links on this page.