Three vs O2: comparing 4G/5G coverage, speeds & benefits
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Will you get a better 4G/5G signal on O2 or Three? Which has faster speeds? Who has the best roaming? Our comparison reveals the answers. Last updated: 25th June 2025
What we compare in this guide
Quick update on latest offers
Comparing O2 and Three's networks
Network coverage on O2 vs Three
We go over which network has better 2G/3G/4G/5G coverage
✔ O2’s coverage is better apart from rural 4G
Three and O2 are separate networks with their own strengths and weaknesses. Three’s biggest strength is their 4G data signal, which now covers more of the UK with better rural signal than O2’s 4G network.
But signal for calls and texts (2G/3G) is better on O2, partly because Three have now removed 3G and never had 2G either. It’s still very rare to be somewhere with zero call signal on O2.
O2 also have the better 5G coverage with a long list of 3200+ locations compared to Three’s 588+. Within those areas, both do a good job of having widespread 5G, not just a few streets.
Now that Three and Vodafone have merged, they will shortly be combining their networks (read their guide here). This will change the story dramatically in Three’s favour vs O2 for coverage.
Useful link: Three’s Big Network Build latest
Use O2 and Three's coverage checkers
Don’t just check at home but everywhere you’ll use your phone
Our verdict on coverage:
Current win for O2
"Looking at today’s picture, overall coverage is better on O2. But it’s worth looking ahead to Three and Vodafone combining networks, which will happen free and within months if you join Three today.”
Data speeds on Three vs O2
Do you get faster data speeds on O2 or Three?
✔ Three are faster for both 4G and 5G data
It’s pretty clear from independent network testers that Three customers get better data speeds than O2. This applies across the board on 4G and 5G data.
Opensignal put typical 4G downloads on Three at 38 Mbps vs 23.1 Mbps on O2. Both are perfectly adequate for even doing things like UHD video streaming. We do always find O2 noticeably a bit laggier.
With 5G, the difference is starker. Three have gone about building the UK’s fastest 5G network by securing more spectrum. Opensignal and Speedtest put Three’s typical 5G at 208.9 or 276.1 Mbps but O2’s at just 80.1 Mbps or 85.1 Mbps.
Of course, in reality you will experience higher and lower than these averages. Three set some eye opening top speeds. But rural or weak 4G can see you bump along as slow as 5 - 7 Mbps on either.
Useful link: O2’s guide to their 5G
Our verdict on data speeds:
A win for Three"For 5G it’s hardly a competition as Three are by far the fastest 5G network while O2 are by far the slowest. 4G is a bit closer with O2 having faster top speeds, but Three are generally more consistent. Three win this one easily."
WiFi calling on O2 vs Three
Which provider has the better WiFi calling and other network features?
✔ Three have better WiFi calling and similar extra features
Both WiFi calling and 4G calling (VoLTE) are standard on O2 and Three and let you connect to calls using WiFi and 4G signal. Both providers let you send SMS texts and transfer from WiFi to 4G without calls dropping.
The main difference is in the devices they support. O2 support fewer Android devices. Phones not bought from each network are more likely to work with Three’s WiFi calling than on O2.
One big advantage O2 have over Three is their massive network of WiFi hotspots. They’re free, will save you data and your O2 SIM will connect to them without having to login at many sites. Three only have WiFi on TFL.
Both networks offer eSIM now (see O2’s page here and Three’s here). Call forwarding works on both. But Three still don’t properly support Visual Voicemail but O2 do.
Useful link: See Three’s guide to WiFi calling
Our verdict on extra network features:
Minor win for Three"Three’s more flexible WiFi calling just about pips it for us in this category. Though if you need visual voicemail, O2 are your only choice. There’s not a massive different here."
Perks and benefits: O2 vs Three
Inclusive roaming: O2 Travel vs Three Go Roam
Which provider is better for using your SIM abroad?
✔ O2’s inclusive EU roaming is better than Three’s
Between the two networks, only O2 offer inclusive EU roaming on all their plans. Three don’t offer it as standard, you’ll need to take a slightly more expensive Value or Complete plan or Pay As You Go to get it:
For trips to the EU, O2 are the better choice. You don’t have to worry about running out of roaming passes or paying extra. There is a 25GB data limit but that’s more than Three’s monthly limit of 12GB.
Outside the EU, Three probably beat O2. With a Value or Complete plan, you can use your included roaming passes in these 160+ worldwide destinations.
On O2 you can get worldwide roaming as a paid Extra, but the data allowances are very restrictive (around 150MB per day, so not particularly useful).
Useful link: All roaming costs on O2
Our verdict on inclusive roaming:
A win for O2"When it comes down to it, O2 let you roam in the EU with fewer restrictions and on every single plan. Three will be the better choice for long-haul travellers, but most people will care about not paying extra to roam in the EU."
Extra benefits on O2 vs Three
What other benefits do you get on either network?
✔ O2’s Priority rewards app still better than Three’s
You get access to O2’s popular rewards scheme they call “Priority” on every SIM only and phone contract. This gives you special offers on high street food, drink and shopping for being on O2 and more:
With Priority you’ll get access to presale tickets to concerts or events hosted at an O2 owned or sponsored venue as well as special treatment at the event (here’s what you can expect).
Three do also have a rewards app that gives you access to presale tickets to certain events (read more here). But you don’t get the special treatment you do on O2 Priority, it’s just the presale access.
Overall Three+ is just not as well established as O2’s Priority. You’re more likely to get the most out of O2’s rewards app which is what really counts when it comes down to this kind of benefit.
Useful link: See everything you get with Priority
✔ Three’s premium plans can be worth a look at
Both Three and O2 include more benefits on plans in the higher price range. This includes the worldwide roaming passes on Three and O2’s Travel Inclusive Zone benefit mentioned above and more:
Three offer a three year extended warranty on Value and Complete plans if you take out a phone. And on Complete 24-month phone plans you’ll also get a free screen repair, which is all good if you’re a bit clumsy.
Plus Three give you a Paramount+ subscription that lasts half your contract on Value plans and your entire contract on Complete ones. O2 offer free trials to these streaming services on higher end plans instead.
O2 complicate things by changing the length of this trial depending on the price of your plan. Three’s premium deals give you better worldwide roaming and handy protections for your phone, giving them the win here.
Useful link: Three’s guide to their Plus and Premium plans
Our verdict on extra perks:
Depends what you want"In our eyes, the benefits you get on either network are different enough that some will prefer one or the other. We can’t really say one is objectively better, it really depends on what you want out of your plan."
Comparing pricing and deals on O2 and Three
SIM only deals on Three and O2
Which provider offers better prices on SIM only?
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A win for Three"Three’s different plan tiers make it a bit more complicated to compare the two for sheer value. But Three generally offer more data for lower prices, even on their Value and sometimes on their Complete plans. Three take this one."
Special offers available on O2 and Three
Here's what promotions Three and O2 have running this month
Phone contracts compared on O2 and Three
Which provider gives you better flexibility or price on their phone plans?
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✔ O2 offer better flexibility on their phone contracts
Both O2 and Three offer phone contracts based on finance agreements (basically loans) that split the cost of your phone and your usage (mins, texts, data) plan into separate payments. So what are the differences?
Well, O2 let you choose the length of your contract between 3 and 36 months how you like it and set the upfront fee as you want. Three only let you choose a contract length of 12, 24 or 36 months.
That extra flexibility will make O2 more appealing for a lot of people. It’s worth knowing that both let you pay off the cost of your phone and upgrade whenever, so that’s not a point of comparison between them.
However, Three do tend to be better on price than O2. But if you’re looking for the best deal possible it’s also worth checking third party resellers (their deals are listed in our comparison tool).
Useful link: Use our phone contract comparison tool
Our verdict on phone contract prices:
Depends on what you want"While the price of phones is similar on both, Three’s cheaper usage plans will save you quite a lot in the long run. But some will prefer the better flexibility on O2. It really comes down to what you prefer here."