Best SIMs on O2: 100GB for £12, 75GB for £10
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See how we rate each of the choices on O2's SIM only, compared with other UK mobile networks' closest plans. Last updated: 17th April 2026.
O2's best SIM only deals
This month's best SIM only deal on O2
just
£12
a month
✔ Unlimited mins and 100GB data See full deal
at o2.co.uk
(opens in new window)
Looking at what you can get on SIM only with O2 this April, our best-rated deal would be their discounted 12‑month plan below, which comes with 100GB data, plus unlimited minutes and texts for £12 a month:
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 other networks you can beat it on:
Their £10 for 75GB plan is a decent deal for April
just
£10
a month
✔ Unlimited mins and 75GB data See full deal
at o2.co.uk
(opens in new window)
For people who don't need that much 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 75GB data, unlimited minutes and texts for £10 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 the networks with cheaper plans here:
They're also offering 40GB for £8 on SIM only currently
just
£8
a month
✔ Unlimited mins and 40GB data See full deal
at o2.co.uk
(opens in new window)
If that'd be too much data for you, have a look at O2's discounted 40GB SIM below at £8 a month, as it's another good deal. It's on a 12‑month plan and comes with 40GB data, unlimited minutes and texts:
There are other networks charging less for a SIM with 40GB data or more but this is the best current option with a provider that uses O2. 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