Unlimited data.
Actually unlimited.
Compare unlimited data SIM deals from the UK's leading networks. No bloated phone contracts, just the data you need at a price that makes sense.
The cheapest unlimited data SIM on a 12-month plan is Lebara at £22.50 per month with unlimited UK calls, texts, and 100 international minutes. For a no-contract option, Chattr offers unlimited data for £20 per month on a 30-day rolling basis. Asda Mobile at £19 per month is the best value on a 24-month deal.
Best unlimited data SIM deals right now
Lebara Unlimited Data (12 month)
Lebara Unlimited Plus (12 month)
Chattr Unlimited
Asda Mobile Unlimited
Lebara Unlimited Plus (30 day)
How the plans compare
| Network | Price/month | International calls | No contract | Underlying network |
|---|---|---|---|---|
| Lebara Unlimited (12M) | £22.50/month | 100 intl mins included | No (12 month) | Vodafone |
| Lebara Unlimited Plus (12M) | £27.00/month | Unlimited intl mins | No (12 month) | Vodafone |
| Chattr Unlimited | £20.00/month | UK only | Yes (30-day) | O2 |
| Asda Mobile Unlimited | £19.00/month | UK only | No (24 month) | Vodafone |
| Lebara Unlimited Plus (30D) | £30.00/month | Unlimited intl mins | Yes (30-day) | Vodafone |
Prices shown are indicative. Click through to see current offers and confirm availability.
What you need to know before you choose
Unlimited data SIM deals have got genuinely good value over the past couple of years. You no longer have to pay a premium for the peace of mind of not watching your data counter. The question now is less about whether to go unlimited and more about which network and which contract length makes sense for you.
Is unlimited data actually unlimited?
For almost all practical purposes, yes. Most UK networks do not impose a hard data cap on unlimited plans. What some networks do have is a fair use policy that can throttle your speed after extremely heavy usage in a short period, we are talking about downloading hundreds of gigabytes in a single session. For normal streaming, browsing, and working, you will never hit it.
One thing worth checking: some cheaper unlimited plans cap your maximum download speed even if the data itself is unlimited. If you want genuinely fast 5G speeds rather than just unlimited slower data, look at the speed tier on the plan before you buy.
24-month contract or 30-day rolling?
The longer the contract, the cheaper the monthly price. Lebara's 12-month unlimited plan at £22.50 is cheaper per month than their 30-day rolling equivalent. Chattr's 30-day plan costs a similar amount but you can cancel any time with no penalty.
If your phone is in good shape and you are not planning to upgrade for a while, locking into a 24-month SIM deal at a low rate is smart. If you are likely to want flexibility, moving abroad, upgrading your phone, or just not wanting to commit, the rolling plan is worth the extra cost.
Does it matter which network the SIM runs on?
More than people realise. None of the providers on this page own their own network infrastructure. They rent capacity from the big four operators and pass the savings on to you. The coverage you get is effectively the same as the parent network.
Asda Mobile and Lebara both run on the Vodafone network. Chattr runs on O2. If you already know your area has great O2 coverage but weaker Vodafone signal, or vice versa, that is worth factoring in. Check coverage at your home address and your regular locations before you commit. See our full phone and SIM comparison for more.
Questions people ask
The cheapest unlimited SIM we currently compare is Asda Mobile at £19 per month on a 24-month contract. If you want the flexibility of a rolling plan with no commitment, Chattr offers unlimited data for £20 per month on a 30-day rolling basis.
For normal use, yes. Most UK networks do not apply a hard cap. Some have fair use policies that may reduce speeds after very heavy usage in a single session, but this rarely affects typical users. Always worth checking the specific terms of the plan before you buy.
Of the providers we compare, Chattr runs on O2 and both Asda Mobile and Lebara run on the Vodafone network. O2 and Vodafone both have strong nationwide coverage. The best choice depends on which has the stronger signal at your specific location.
Yes. Chattr offers unlimited data on a 30-day rolling plan at £20 per month, and Lebara's Unlimited Plus is also available on 30-day terms at £30 per month. You pay month to month and can cancel any time.
Most do now, but check the specific plan. Some entry-level unlimited deals cap you at 4G speeds even with unlimited data. If 5G matters to you, confirm the plan explicitly includes 5G access and that your handset supports it.
Related deals and guides
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