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O2 SIM only deals: comparing their best plans in September

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We look at whether O2's current best SIM only plans are decent value compared to all their competitor mobile networks in the UK. SIM Sherpa is your trusty guide. Last updated: 28th September 2023.

O2's best SIM only deals

The best overall O2 SIM only deal this month

O2 SIM card
30GB data
a month

24-month dealGet this deal

(opens in new window)

We think O2's best value option on SIM only this September is their £19.99 a month plan below, which comes with 30GB data, plus unlimited minutes and texts on a 24‑month deal:

Even though it's in our pick of O2's best SIM only deals, you can actually beat it on price with other providers, including ones that also use the O2 network. See the networks with cheaper plans here:

O2's 12GB for £16.99 plan is a good option too

O2 SIM card
12GB data
a month

24-month dealGet this deal

(opens in new window)

For less monthly data, the next best SIM only plan on O2 in our opinion is their 24‑month one below. For £16.99 a month, you get 12GB data, plus unlimited minutes and texts:

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:

Their £25 for 250GB plan is a decent deal for September

O2 SIM card
250GB data
a month

24-month dealGet this deal

(opens in new window)

For even more monthly data, another good deal on O2 at the moment is their £25 SIM only plan here, which includes 250GB data instead, plus unlimited minutes and texts:

It's a good enough deal to get into O2's best SIMs but you can actually get a lower price for a similar plan elsewhere, even if you definitely want it to use the O2 network. See where you can get it for less here:

They're also offering 150GB for £22.99 on SIM only currently

O2 SIM card
150GB data
a month

24-month dealGet this deal

(opens in new window)

For a smaller amount of data, our next best pick of O2 SIM only plans is their 24‑month £22.99 deal below, which gets you 150GB data and unlimited minutes and texts:

It might not be the lowest-cost SIM only deal with 150GB 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:

Compare all SIM only plans

Compare deals from all networks

How O2's deals compare with other networks

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More about O2's SIM only plans

O2’s SIM only prices and benefits compared

Rating stars and O2 logo

What we generally think about O2Read our full review

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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

O2 coverage checker screenshot

Check signal before you buy your planCheck yours now

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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

Other O2 guides