O2's best SIMs: 20GB for £8, 80GB for £10
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Find out which choices on O2's SIM only came top of our comparisons against every other UK network this month. Last updated: 23rd February 2026.
O2's best SIM only deals
The best overall SIM only deal this month on O2
just
£10
a month
✔ Unlimited mins and 80GB data See full deal
at o2.co.uk
(opens in new window)
Looking at all O2's options on SIM only this February, the deal that jumps out to us is their discounted 80GB for £10 one below. It's a 12‑month plan and comes with unlimited minutes and texts too:
It's currently the best priced 80GB data or more SIM only deal on a provider using the O2 network, even if you can beat it on price if you're open to ones not on O2. Here's which other networks can beat it:
We also like their £8 for 20GB plan
just
£8
a month
✔ Unlimited mins and 20GB data See full deal
at o2.co.uk
(opens in new window)
For those with smaller data needs, 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 20GB data, unlimited minutes and texts for £8 a month:
It's actually possible to beat this deal if you're not fussed whether your SIM is with a provider using the O2 network. But if you are, it is the current best-priced option. See where you can get it for less here:
Their 40GB for £8.50 SIM is another good option
just
£8.50
a month
✔ Unlimited mins and 40GB data See full deal
at o2.co.uk
(opens in new window)
To satisfy bigger data needs, have a look at O2's discounted 40GB SIM below at £8.50 a month, as it's another good deal. It's on a 12‑month plan and comes with 40GB data, unlimited minutes and texts:
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 the networks offering it cheaper:
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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