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 we compare is Chattr's Freedom One at £15 per month on a 30-day rolling plan, on O2 with no price hikes and no credit check. If you are happy to commit, iD Mobile's unlimited is £16 per month on 24 months with no annual price rises, and Asda Mobile is £19 on 24 months or £22 with a 12-month price lock on Vodafone coverage. O2's Unlimited Classic is £23 direct on a promo that runs to 4 November.
Best unlimited data SIM deals right now
Chattr Freedom One (Unlimited)
iD Mobile Unlimited (24 months)
Asda Mobile Unlimited
O2 Unlimited Classic
1p Mobile Unlimited
VOXI Unlimited
How the plans compare
| Network | Price/month | Contract | Standout | Underlying network |
|---|---|---|---|---|
| Chattr Freedom One | £15.00/month | 30-day rolling | No price hikes, no credit check | O2 |
| iD Mobile Unlimited | £16.00/month | 24 months (£18 rolling) | No annual price rises | Three |
| Asda Mobile Unlimited | £22.00/month (£19 on 24M) | 12 or 24 months | Price locked for the term | Vodafone |
| O2 Unlimited Classic | £23.00/month | 24 months, offer to 4 Nov | O2 Priority perks | O2 (direct) |
| 1p Mobile Unlimited | £25.00/30 days | 30-day rolling | 5G with no speed caps | EE |
| VOXI Unlimited | £35.00/month | 30-day rolling | No speed restrictions | Vodafone |
Prices checked on each provider’s website, 4 October 2026, and may change. 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. 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. 1p Mobile and VOXI both advertise no speed caps on their unlimited plans.
Do I still need a long contract for unlimited data?
No, and Chattr's Freedom One at £15 on a 30-day rolling plan is still the cheapest unlimited data we compare, with no mid-contract price hikes, which the big networks can't say. What has changed is that committing now saves real money for the first time: iD Mobile's unlimited drops to £16 on a 24-month plan with no annual price rises, and Asda Mobile's drops to £19 on 24 months. If you want the door left open, the rolling versions cost a little more: iD at £18, 1p Mobile at £25, VOXI at £35.
Watch the printed price rises too. O2's £23 offer rises to £25.50 in April 2027 and £28 in April 2028, which is typical of the big networks now. Chattr, iD and VOXI all commit to no rises on these plans, so compare what you will pay across the whole term, not just month one.
Does it matter which network the SIM runs on?
More than people realise. Most providers on this page don't own their own network infrastructure. They rent capacity from the big four operators and pass the savings on to you. Between them they cover all four: Chattr runs on O2, iD Mobile on Three, Asda Mobile and VOXI on Vodafone, and 1p Mobile on EE, while O2's Unlimited Classic puts you on the host network directly. Check coverage at your home address and regular locations before you commit. See our full SIM only comparison for more options.
Questions people ask
The cheapest unlimited SIM we currently compare is Chattr's Freedom One at £15 per month on a 30-day rolling plan, on O2 with no price hikes and no credit check. If you are happy to commit, iD Mobile's unlimited is £16 per month on 24 months with no annual price rises, and Asda Mobile's is £19 per month on 24 months on Vodafone coverage.
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.
The providers we compare cover all four UK host networks: Chattr runs on O2, iD Mobile on Three, Asda Mobile and VOXI on Vodafone, and 1p Mobile on EE. The best choice depends on which host network has the stronger signal at your specific location, so check coverage at your address first.
Yes. Chattr at £15, iD Mobile at £18, 1p Mobile at £25 and VOXI at £35 all offer unlimited data on rolling plans, so you pay month to month and can cancel any time. The contract versions are now cheaper though: iD is £16 and Asda is £19 on 24 months.
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
Not sure which unlimited SIM is right for you?
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