Best SIMs on O2: 75GB for £10, 40GB for £8
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We've checked through all the SIM only plans available on O2 this month to find which stack up best against the competition. Last updated: 15th May 2026.
O2's best SIM only deals
Our favourite current O2 SIM only deal
just
£10
a month
✔ Unlimited mins and 75GB data See full deal
at o2.co.uk
(opens in new window)
We'd say the best SIM only plan O2 are selling this May is their discounted 12‑month 75GB deal below, which comes in at £10 a month and includes unlimited minutes and texts too:
While this is a good enough deal to make it into the best of O2's SIMs, you can beat it for price (even if you definitely want a provider that uses the O2 network). Here's which other networks can beat it:
£8 for 40GB is O2's next best SIM deal in May
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, you might like the discounted £8 SIM only deal running on O2 at the moment. It's a 12‑month plan, which comes with 40GB data, unlimited minutes and texts too:
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:
There's also a nice 250GB for £15 plan with them this month
just
£15
a month
✔ Unlimited mins and 250GB data See full deal
at o2.co.uk
(opens in new window)
For people who need 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 250GB data, unlimited minutes and texts for £15 a month:
In comparison to the rest of O2's current SIM only plans, it's one of the best. But it is beatable on price, even if you're set on joining a provider that uses the O2 network. 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