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Three vs O2: comparing 4G/5G coverage, speeds & benefits

Three vs O2

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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: 16th November 2021

What we compare in this guide

Quick update on latest offers

Comparing O2 and Three's networks

Network coverage: do Three or O2 have better signal?

Comparing O2 vs Three on 5G, 4G and 3G

Mobile signal bars with O2 and Three logos

O2's 4G / 3G coverage mix is better than Three’s

O2 best network for coverage banner

See latest awards

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Three and O2 are separate companies running on their own wholly-separate networks. Each has got its pros and cons in terms of the quality of signal you’ll get.

Generally, basic 2G and 3G for calls and texts is more widespread on O2 than Three. They’ve got more of the country’s physical landmass covered, fewer rural blackspots and better indoor signal.

The advantage for O2 vs Three on 4G data signal (see 5G below) is less clear-cut. Three probably have slightly larger areas of the country covered but O2 are better in mid-size towns.

A lot of it will come down to which is better in the places you'll use your phone, so make use of their coverage checkers below - and don't just look at home. Think about everywhere you're likely to go regularly.

Useful link: Three’s Big Network Build latest

5G is live on both O2 and Three

Three's 5G locations map

See next 5G cities

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5G is live on both O2 and Three. And you’ll get it included in all their SIM only plans and compatible phone contracts at no extra cost on both (but you’ll need to select 5G in O2’s checkout to get it).

On paper, Three are winning the 5G rollout against O2. They’ve got it in 300+ locations, compared to O2’s 190+ places. But you should be aware that being on either list doesn’t mean the entire place has 5G.

In real-life we’d again recommend checking each’s predicted 5G coverage, because their maps show the precise streets where they predict 5G is live.

We’ve also found in real-life testing that the experience dwindles quite quickly to below 4G-quality if you’re only on the edge of a 5G coverage area.

Useful link: Latest O2 5G rollout news

Use O2 and Three's coverage checkers

Check at home, your route to work/school and anywhere you'll use your phone

Three's coverage checker

Three coverage checker

Check Three signal

on their official map
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O2's coverage checker

O2 coverage checker

Check O2 signal

on their official map
(opens in new window)

Our verdict on coverage:

O2 win

"We’d still say O2 are the winner here vs Three, because their calling coverage is superior. But Three are catching up, especially as 5G becomes more and more important."

Compare pricing and deals

Data speeds on O2 vs Three

Is data faster on Three or O2?

O2 and Three logos with a speedometer icon

Three's 4G typically faster than O2’s

O2 4G banner

What O2 say...

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Data speeds are O2’s long-term historical weakness. In independent network testers Opensignal and Speedtest’s reports, O2 always come out on bottom (and so below Three) for 4G downloads.

Three tend to tussle with Vodafone in joint-second place, behind the leaders EE. Expect typical speeds in the range 21.60 Mbps for Three but 16.95 - 18.00 Mbps for O2.

From our user tests of both networks, we do find O2 noticeably slower than the rest. But if you’re a basic user that just wants to check emails, the news and browse a bit, they’re still suitable.

While in our Three review, we found their 4G more suitable for demanding things like streaming videos in high definition without buffering. And more consistent in sub-urban areas.

Useful link: Three carry more data than any other network

Three’s 5G is measuring up faster too

Three fastest 5G network banner

Read why

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If Three have the speed advantage over O2 for 4G, it’s looking like they’ll keep it up for 5G too. Three have bought the most spectrum of any network and it’s all next to each other in the frequency range.

Three say this means they’ll be the UK’s fastest 5G network. And it’s certainly looking like that in early testing - with Three coming in at 191.50 Mbps vs O2 on 130.04 Mbps.

Those are both home fibre optic broadband beating speeds. And the difference between is unlikely to be noticeable in reality, unless you're downloading massive files like Xbox games over a mobile connection.

But if you’re the type of person that does speed tests for fun or wants to have the bragging rights, it’s looking like Three will be the better choice for the timebeing.

Useful link: Why Three say theirs is fastest

Our verdict on data speeds:

A win for Three

"Three’s typical 4G and 5G speeds come out faster than O2 in independent network testing based on millions of measurements. It’s a pretty easy verdict here."

Compare pricing and deals

WiFi calling on Three vs O2

O2 and Three both offer WiFi calling. We look at which is best

WiFi calling symbol with O2 and Three logos

Three's WiFi calling is better than O2’s

Three WiFi calling

See Three's scheme

(opens in new window)

Both networks have long offered WiFi calling and 4G calling (VoLTE). These let your phone make and take calls over WiFi or 4G where traditional 2G/3G calling signal is lacking - boosting indoor coverage.

O2 and Three’s technology is similar but we’d say there are a couple of advantages to WiFi calling on Three:

It supports SMS text messages over WiFi too. O2’s does not. You might not send many but things like banks use SMS as a verification method, so it’s handy to be able to receive them with bad signal.

We also think Three are easier to join with Android phones and have the feature work. O2 are a little cagey on supporting models that weren’t bought from them and have their settings pre-installed.

In our tests for our best WiFi calling networks page, we found even older Android models not bought from Three still worked on the network.

Useful link: See Three’s guide

Our verdict on WiFi calling:

Win for Three

"Not only do we think you've got a better chance of Three supporting your phone than O2 but you'll also get the useful advantage of SMS text messaging over WiFi."

Compare pricing and deals

WiFi hotspots on O2 vs Three

Do you get more free WiFi access on Three or O2?

WiFi symbol with O2 and Three logos

O2 customers get extra benefits on O2 WiFi

Free O2 WiFi hotspots

Find nearby hotspots

(opens in new window)

There might be loads of free WiFi around nowadays and you might have a massive data allowance but we still like mobile networks that have some sort of free WiFi hotspot provision with your deal.

And O2 have one of our favourite schemes. You probably know the O2 WiFi hotspot network: it’s over 15,000 free hotspots on useful places like shops, food and drink venues and on transport.

As an O2 customer, about a third of these hotspots will recognise your O2 SIM card and automatically connect you, without ever having to hit a login screen or choose it. We’ve tried it for our O2 review.

If you guard your data preciously, it’s a useful feature as the data doesn’t come out of your allowance. And if you’re a regular in London, free WiFi on the TFL network is handy.

Useful link: Find hotspots near you

Three's only free WiFi is on the London Underground

Free WiFi on the Underground

How it works

read Three's official guide
(opens in new window)

The closes Three can get to O2 WiFi is that they take part in the same free WiFi on the London Underground (and Overground) network scheme.

It means you’ll be able to stay connected even underground on the station platforms but not in the tunnels. It works on pay monthly and pay as you go, as long as you have an active add-on.

Other than that, there’s no free WiFi available on Three. If you’re worried about data usage though, do have a look at their unlimited data plans. Here’s their current cheapest:

Useful link: How to get free WiFi on the Underground with Three

Our verdict on free WiFi:

Win for O2

"Connecting automatically to some O2 WiFi hotspots is a handy little benefit for O2 customers, although we'd probably not make it the crucial deciding factor between the two."

Compare pricing and deals

Perks and benefits: O2 vs Three

Inclusive roaming: O2 Travel vs Three Go Roam

Are Three still better than O2 for roaming?

A globe with O2 and Three logos

O2 have kept EU roaming on their plans

Free O2 EU roaming

See costs per country

in O2's international guide
(opens in new window)

All the UK’s main mobile networks (Three, Vodafone and EE) have been removing inclusive EU roaming from their plans. O2 are the last main network to keep it (alongside all these providers).

Take any pay monthly or pay as you go plan from O2 (phone or SIM) and you’ll be able to use your phone at the same cost within the EU as you can at home - use your plan’s allowances there for free.

And select plans even include some token daily minutes, texts and data to use in a further 27 extra non-EU destinations to keep you ticking over. Look out for O2 Travel Inclusive zone.

There is a fair usage policy while you’re roaming in the EU. It’s set at 25GB per month (if your plan is that big). If you go beyond, you will end up paying extra at these rates.

Useful link: All roaming costs on O2

Three’s inclusive roaming is effectively finished

Expired stampThree Feel At Home roaming

See what’s changed

(opens in new window)

As we’ve mentioned, O2 are the only main network operator that’s kept EU roaming, including Three. If you sign up as a new customer now, you’ll only get it until May 2022 - after that it’s chargeable.

This is a big change from their previously unbeatable Go Roam offer, which gave you inclusive roaming in 71 countries - both inside and outside the EU.

You’ll now pay £2 per day within the EU to access your regular monthly minutes, texts and data. And £5 per day in countries outside the EU. That will add up fast on a two-week holiday.

If you want access to the Three network and to have EU roaming included, you’re now actually better off joining Three’s sub-brand SMARTY who’ve kept the benefit.

Useful link: Full guide to roaming on Three

Our verdict on inclusive roaming

A win for O2

"A year ago this would have been a clear win for Three. But now they’ve ditched Go Roam, it’s O2 that win out on roaming for us."

Compare pricing and deals

Other added perks on Three vs O2

What else do O2 and Three add to sweeten the deal?

Giftbox with Three and O2 logos

O2 Priority is a nice perk

O2 Priority rewards scheme

See available deals

(opens in new window)

Whether you join O2 on pay monthly or pay as you go, you instantly become eligible for their well-known rewards scheme: Priority. There’s quite a lot to it, here’s what it includes:

Priority members get first dibs on tickets where O2 are the venue or event sponsor, plus special treatment while you're at the event itself (here's some examples of what to expect).

And then the app throws offers at you on shopping on the high-street and online, travel and occasional freebies like free coffee and other voucher-site style deals.

You’ll probably know if it’s the sort of thing you’d use and enjoy. We’d probably not say it’s the sole reason to join O2 but Priority is nice little extra to sweeten the deal. Three once had a similar app but they scrapped it.

Useful link: See everything you get with Priority

Get an O2 Extra with pay monthly plans

Extras on O2

See all choices

(opens in new window)

To add a bit more value to their pay monthly plans on phone contracts and SIM only, O2 offer up free trials to some premium subscription services, which they brand as O2 Extras.

The services in the scheme include Disney+, Amazon Music, Prime Video or Audible, or any of these other apps. The trial covers the cost of the subscription, you don’t get any free data for streaming.

They’re only trials, not freebies. After your trial is up, you pay for the service via your mobile bill. And the trial length depends on what plan you choose (premium plans include longer trials).

But if you were already thinking of signing up to a long, premium plan with O2, getting a 12-month trial on one of these services will add genuine value. And it’s something Three don’t offer.

Useful link: Full O2 Extras FAQs

Three are getting a bit no-frills nowadays

Three Big Network Build

What’s involved

(opens in new window)

As we’ve noted in our full review of Three, they’ve changed their strategy from offering lots of wraparound benefits with your mobile plan to concentrating on the quality of their actual mobile network.

That’s fair enough but we have seen quite a few nice benefits disappear recently. Inclusive roaming is gone, free streaming data gone, rewards app gone and even mad stuff like easyJet upgrades are no more.

Three are in danger of becoming no-frills. And you now get fewer added perks than joining O2. Fortunately on SIM only, at least Three’s pricing is way more competitive.

It’s actually got to the point where if you’re not fussed about 5G or having telephone customer service, you’re almost better off joining Three’s sub-brand SMARTY on a SIM.

Useful link: Read our SMARTY vs Three guide

Our verdict on extra perks

Win for O2

"If you'd asked us two years ago, it'd be a slam dunk for Three. But now they've removed loads of benefits, it's O2 that come out on top in this category."

Compare pricing and deals

Comparing pricing and deals on O2 and Three

SIM only plans on O2 and Three

Are Three always cheaper?

O2 and Three logos with a SIM card



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Added features

SIM only plan prices

A win for Three

"Use the deal finder above and you'll notice Three's SIMs are usually cheaper for the same minutes, texts and data. Keep an eye out for special offers that can even out the playing field from time to time."

Compare pricing and deals

Special offers available on O2 and Three

Here's what promotions Three and O2 have running this month

O2 and Three logos with a special offer ribbon

Phone contracts compared on Three and O2

Which network has better phone contracts?

O2 and Three logos with smartphone icon

O2's phone contracts are more flexible

O2 custom plans

See custom plans

(opens in new window)

There are two ways to get a phone contract on O2. You can buy directly from O2 (which we’ll talk about below) or you can join via third party retailers, which can offer cheaper prices. We compare both options here.

Joining directly via means you’ll be put onto their Custom Plans (also known as Refresh). These split your phone deal down into finance for the cost of the phone and airtime for your minutes, texts and data.

For you, that brings lots of flexibility. You can play around with contract lengths and upfront fees to get a combo that works for you - it doesn’t affect the full cost of the phone either.

And once the phone is paid off (which you can choose to do early), you’ll only have your airtime to pay. So at the end of your deal, your monthly cost drops. Or you can choose to leave early. Or upgrade to a new phone.

The device costs directly from O2 are actually pretty cheap. It’s just the airtime that’s a killer (it’s expensive). So joining on shorter contracts can make O2 more competitive on price than Three.

Useful link: Use our phone contract comparison tool

Three's phone contracts are more conventional

Compare phone contract prices

Use phone deal finder

(opens in new window)

Like O2, you can also join Three on a phone contract in two ways. Join them directly via their website or in-store. Or take a deal from retailers that provide the phone themselves and can offer better prices. Compare here.

Unlike O2, there’s no financing involved, so you don’t get the flexibility to choose contract lengths (they’re all 24 months), your upfront and you can’t do stuff like upgrade early without buying yourself out.

But we would say Three’s phone contracts on a comparable 24-month deal to O2 do tend to work out cheaper on the whole (though a lot depends on current offers).

We’d also say that the lack of handset financing means the credit requirements to join Three on a phone contract are probably a little less tight than on O2, because they’re not effectively acting like a bank giving out loans.

Useful link: Use our phone contract comparison tool

Our verdict on phone contract prices:

Three marginally cheaper

"We can say Three are cheaper on average than O2 but the smart thing to do is use our comparison tool to look at precise costs for the mins, texs and data you want."

Compare phone prices

More guides about Three

Other O2 guides