Best SIM deals on O2: 100GB for £10, 20GB for £7.50
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We've compared pricing on all of O2's pay monthly SIM only to find which ones stack up best against the rest of the market. Last updated: 20th January 2026.
O2's best SIM only deals
Our favourite SIM only deal of the month on O2
just
£10
a month
✔ Unlimited mins and 100GB data See full deal
at o2.co.uk
(opens in new window)
From all the options O2 have got available this January on SIM only, we think this discounted £10 12‑month deal is their best. For your £10 a month, you get 100GB data alongside unlimited minutes and texts:
There are other networks charging less for a SIM with 100GB data or more but this is the best current option with a provider that uses O2. Here are other networks you can beat it on:
Their £7.50 SIM with 20GB is our next favourite this January
just
£7.50
a month
✔ Unlimited mins and 20GB data See full deal
at o2.co.uk
(opens in new window)
For people who don't need that much data, we think this discounted 20GB 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 £7.50 a month:
It can actually be beaten on price if you don't need your SIM to be with a provider that uses the O2. If you do need that, it is the cheapest SIM with 20GB data or more. See the networks with cheaper plans here:
We also like their £8 for 40GB plan
just
£8
a month
✔ Unlimited mins and 40GB data See full deal
at o2.co.uk
(opens in new window)
For more data, we also think this discounted £8 O2 SIM is one of their best options. It comes with 40GB data, unlimited minutes and texts on a 12‑month deal:
This isn't the very cheapest deal with 40GB data or more out now. But if you definitely need a SIM only plan that uses the O2 network, we think it is the best option. Here's which other networks can beat it:
Their 80GB for £9.50 SIM is another good option
just
£9.50
a month
✔ Unlimited mins and 80GB data See full deal
at o2.co.uk
(opens in new window)
If you're even more data-hungry, O2's discounted £9.50 SIM below is another of their best deals this month. For £9.50 a month, it offers 80GB data, unlimited minutes and texts on a 12‑month plan:
You can get a lower-priced SIM with 80GB data or more elsewhere if you don't need it to use the O2 network. But if you do need that, it is the cheapest deal available. See where you can get it for less here:
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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