Best SIMs on O2: 40GB for £8, 80GB for £10
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See the most competitive options on O2's SIM only this month. We've compared them against other networks to find the best. Last updated: 15th June 2026.
O2's best SIM only deals
The best SIM only deal on O2 this month
just
£8
a month
✔ Unlimited mins and 40GB data See full deal
at o2.co.uk
(opens in new window)
Out of all the SIM only plans available this June on O2, we'd say their best value deal is their discounted 12‑month SIM below, which gets you 40GB data, plus unlimited minutes and texts for £8 a month:
It might not be the lowest-cost SIM only deal with 40GB data or more on the entire market but if you're sure you need a SIM using the O2 network, it is the best-priced. Here are other networks you can beat it on:
Or their £10 for 80GB SIM plan is worth a look too
just
£10
a month
✔ Unlimited mins and 80GB data See full deal
at o2.co.uk
(opens in new window)
For more monthly data, you might like the discounted £10 SIM only deal running on O2 at the moment. It's a 12‑month plan, which comes with 80GB data, unlimited minutes and texts too:
If you don't need your SIM to be on a provider that uses the O2 network, you can beat this deal elsewhere. But if you do, it's the cheapest 80GB data or more option. See the networks with cheaper plans here:
O2 are also offering 100GB for £12 on SIM only
just
£12
a month
✔ Unlimited mins and 100GB data See full deal
at o2.co.uk
(opens in new window)
To get even more data, we'd say this is one of O2's best deals on SIM only this month too. It's a discounted 12‑month plan, comes with 100GB data, unlimited minutes and texts for £12 a month:
It isn't actually the cheapest 100GB data or more SIM available overall this month but if you definitely need your plan to use the O2 network, it is the lowest cost option. Here's which other networks can beat it:
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O2’s SIM only prices and benefits compared
In our full review of the O2 network we said we liked their brilliant call signal (3G/2G) coverage, their good 5G coverage and their great WiFi hotspot scheme. We also like their WiFi calling and 4G calling.
You have the choice of 1-month, 12-month and 24-month contracts. Their 24-month contracts are usually much cheaper per month, but it’s best to check their current deals for the best possible offer.
O2’s deals tend to be some of the most expensive of all networks, but they’re a bit more competitive on big data deals. There are some smaller providers on O2’s network who offer better value SIM only deals.
They’re also the only main UK network to still offer inclusive EU roaming on all plans. And you can get extras on premium plans, such as subscriptions to entertainment services and worldwide roaming data passes.
Useful link: Read our full O2 review
Other things to know about O2’s SIM only deals
You’ll get your O2 SIM card between 1-4 working days after ordering (depends on your location). And there are premium delivery options too. You’ll receive each size of SIM for any phone. Or you can take an eSIM.
When your SIM arrives, you have 14 days to return it and get a full refund if you’re not satisfied. This will also cancel your contract. Here’s how you do that.
To prevent customers racking up huge bills they can’t pay, O2 make you pass a credit check to join them. If you have a poor or no credit history you can still join O2 on a PAYG monthly bundle instead.
And if you’re switching to O2 from another network you can keep your number by requesting a PAC from your old provider and giving it to O2 at any point. Here’s how you do that.
Useful link: Compare all O2 SIMs