Best SIM deals on O2: 100GB for £10, 20GB for £7.50
The retailers featured on this page may compensate us when our readers follow links to their websites and make a purchase. More
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: 9th January 2026.
O2's best SIM only deals
The SIM only deal on O2 we rate highest this month
just
£10
a month
✔ Unlimited mins and 100GB data See full deal
at o2.co.uk
(opens in new window)
Out of the best SIM only plans on O2 this January, we think the leading deal is their discounted 12‑month 100GB for £10 one below, which also comes with unlimited minutes and texts:
It isn't actually the cheapest 100GB data or more SIM available overall this month but if you definitely need your plan to use the O2 network, it is the lowest cost option. Here's where you can beat it on other networks:
They've also got a 20GB for £7.50 SIM plan at the moment
just
£7.50
a month
✔ Unlimited mins and 20GB 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 £7.50 a month for 20GB data and comes with unlimited minutes and texts:
You have got other cheaper options if you don't need your SIM to be on a provider that uses the O2 network. But if you do, it is the cheapest current deal available. See lower-priced networks' deals here:
O2's £8 for 40GB is our next best choice now
just
£8
a month
✔ Unlimited mins and 40GB data See full deal
at o2.co.uk
(opens in new window)
For people who need more data, O2 have got a discounted £8 deal on SIM only we think's worth looking at. It gets you 40GB data, unlimited minutes and texts and it's a 12‑month plan:
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 are other networks you can beat it on:
Their £9.50 SIM with 80GB is our next favourite this January
just
£9.50
a month
✔ Unlimited mins and 80GB data See full deal
at o2.co.uk
(opens in new window)
If you want even more data, we think this discounted 80GB 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 £9.50 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 80GB data or more. See the networks with cheaper plans 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