O2's best SIMs: 80GB for £10, 40GB for £8
The retailers featured on this page may compensate us when our readers follow links to their websites and make a purchase. More
We list the best of what's available on O2's SIM only this month, after comparing each plan with other UK mobile networks. Last updated: 31st March 2026.
O2's best SIM only deals
Our highest-rated SIM only deal on O2 this month
just
£10
a month
✔ Unlimited mins and 80GB data See full deal
at o2.co.uk
(opens in new window)
Out of all the SIM only plans available this March on O2, we'd say their best value deal is their discounted 12‑month SIM below, which gets you 80GB data, plus unlimited minutes and texts for £10 a month:
It might not be the lowest-cost SIM only deal with 80GB 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 the networks offering it cheaper:
They've also got a 40GB for £8 SIM plan at the moment
just
£8
a month
✔ Unlimited mins and 40GB data See full deal
at o2.co.uk
(opens in new window)
For a smaller amount of data, another option for you on O2 is their discounted 12‑month SIM below, which costs £8 a month for 40GB data and comes with unlimited minutes and texts:
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 40GB data or more option. See the networks that beat it here:
O2's £12 for 100GB is our next best choice now
just
£12
a month
✔ Unlimited mins and 100GB data See full deal
at o2.co.uk
(opens in new window)
For people who need even more data, O2 have got a discounted £12 deal on SIM only we think's worth looking at. It gets you 100GB data, unlimited minutes and texts and it's a 12‑month plan:
Compared to O2's other deals, this comes out among the best. But it's worth knowing you can get a lower price elsewhere, even on other providers that use the O2 network. Here are the networks where it'd cost less:
Their £15 SIM with 250GB is our next favourite this March
just
£15
a month
✔ Unlimited mins and 250GB data See full deal
at o2.co.uk
(opens in new window)
If you want even more data, we think this discounted 250GB is one of the best SIM only plans on O2 too. It's on a 12‑month deal, comes with unlimited minutes and texts - all for £15 a month:
It might be one of O2's best deals on SIM only but you can get a lower price for a similar plan on other providers, even ones that use the O2 network. See which networks that are cheaper here:
Compare all SIM only plans
Compare deals from all networks
How O2's deals compare with other networks
Networks
Providers:
Plan
Data: (0MB+)
Minutes: (0+)
Thanks, we'll send that out now. Please check your inbox for our email.More about O2's SIM only plans
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