Cookies on the SIM Sherpa website

We use cookies to track which pages on our website readers visit most. This helps us understand which topics people find interesting, to write more articles about them.

You can accept these tracking cookies or choose to block them. You can change these settings at any time.

X close

✖ Tracking cookies deleted and blocked

Ok, we will not track your page views as you move around any part of the SIM Sherpa website. But we will use that one cookie to remember you don't want to be tracked.

Click here to unblock tracking cookies

X close

✔ Cookies accepted

Thank you for accepting cookies for the SIM Sherpa website. This will help us constantly improve our content.

If you ever want to change your cookie settings for our website, go to our Cookies page here.

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

Three vs O2

The retailers featured on this page may compensate us when our readers follow links to their websites and make a purchase. More

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: 18th November 2022

What we compare in this guide

Quick update on latest offers

Comparing O2 and Three's networks

Network coverage: do O2 or Three provide more widespread signal?

How O2 compare to Three for 3G/4G/5G signal

Mobile signal bars with O2 and Three logos

O2 offer a better mix of 2G/3G/4G coverage than Three

O2 best network for coverage banner

See latest awards

(opens in new window)

O2 and Three are two separate networks that provide their own signal using their own infrastructure. Each network has its strengths and weaknesses in terms of signal coverage.

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.

It’s much harder to say which network has the better 4G signal coverage (see 5G below). We’d say Three likely cover more of the UK’s landmass while O2’s signal tends to be 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 expanding on both Three and O2

Three's 5G locations map

See next 5G cities

(opens in new window)

Both O2 and Three have put a lot of effort into expanding their 5G networks. Both offer it on all their SIM only plans and 5G-ready phone contracts at no added cost (you have to check the 5G option in the checkout with O2).

Looking at sheer numbers Three are ahead with 5G live in 300+ locations compared to the 190+ UK towns and cities O2 cover. But neither cover their locations entirely and 5G coverage in these places will vary by network.

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. O2 tend to cover their locations better, but this varies depending on the place.

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
(opens in new window)

O2's coverage checker

O2 coverage checker

Check O2 signal

on their official map
(opens in new window)

Our verdict on coverage:

Win for O2O2 win

"In terms of the overall mix of coverage O2 come out on top. But it’s always worth checking which network has the better coverage in your area before you rule either of them out.”

Compare pricing and deals

Data speeds on Three vs O2

Do O2 or Three offer faster 4G?

O2 and Three logos with a speedometer icon

Three tend to offer faster 4G speeds than O2

O2 4G banner

What O2 say...

(opens in new window)

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

Three are in second place for data speeds, just ahead of Vodafone but far behind EE. Three offer typical speeds around 25.2 Mbps, where O2 offer a comparatively sluggish 17.1 Mbps.

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.

On the other hand, in our review of Three we found their 4G speeds more than good enough for streaming HD videos without buffering and other data-heavy activities. And their speeds remained more consistent in the suburbs than on O2.

Useful link: Three carry more data than any other network

Three offer the faster 5G speeds

Three fastest 5G network banner

Read why

(opens in new window)

Three’s 5G speeds are much faster than the competition. They’ve achieved this by buying up more of the spectrum than the other networks, letting them use frequencies that are closer together.

They claim to be the fastest UK network for 5G and that’s backed up by results from Opensignal and Speedtest by Ookla who put 5G speeds on Three between 103.9 Mbps to a superfast 246.65 Mbps vs 110.9 Mbps - 127.97 Mbps on O2.

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 only looking for the fastest speeds possible then Three will be the best choice. Bear in mind, speeds on the fringes of 5G signal can suffer greatly on both networks. Staying in signal range is key to getting the fastest speeds on both.

Useful link: Why Three say theirs is fastest

Our verdict on data speeds:

A win for Three

"Three win both in terms of 4G and 5G speeds. O2 can tend to be noticeably slower than other networks, so Three are the better choice if speeds are a must."

Compare pricing and deals

WiFi calling on O2 vs Three

Both O2 and Three offer WiFi calling on all plans. Let’s see which scheme is better

WiFi calling symbol with O2 and Three logos

Three offer better WiFi calling than O2

Three WiFi calling

See Three's scheme

(opens in new window)

O2 and Three have offered both WiFi calling and 4G calling (VoLTE) for a while now. These features help to eliminate indoor signal blackspots by letting you make calls via WiFi and 4G signal where conventional 2G/3G call signal is poor.

Both schemes let you send SMS texts over WiFi and 4G as well as letting you move from WiFi signal to 4G signal on a call and have it transfer over without it dropping. So what are the differences?

While both networks support most iPhone models for WiFi calling, O2 tend to support fewer Android models. And Three should support devices not bought directly from them, while O2 are a bit more defensive about supporting phones bought elsewhere.

That doesn’t mean there’s no chance of them working. In our tests for our best WiFi calling networks page, even older Android models not bought from O2 still worked, but you’re more likely to run into compatibility issues with them.

Useful link: See Three’s guide

Our verdict on WiFi calling:

Slight win for Three

"Both networks are similar in how their WiFi calling schemes work now. However, you’re more likely to get it working with Three. It’s not a massive win, but Three take this one."

Compare pricing and deals

WiFi hotspots on Three vs O2

Do Three or O2 offer more WiFi hotspots?

WiFi symbol with O2 and Three logos

O2 offer a massive network of WiFi hotspots

Free O2 WiFi hotspots

Find nearby hotspots

(opens in new window)

While free WiFi is more common these days and data allowances have got larger, it’s still nice when networks help you stay connected and save data on the go by offering free WiFi hotspot access on 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.

These hotspots help you hold onto your data while still using your phone on the go. And if you regularly use the Underground then you’ll also like the free WiFi hotspots on the TFL network that O2 also offer.

Useful link: Find hotspots near you

Three provide free WiFi on the Underground

Free WiFi on the Underground

How it works

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

Three don’t offer the same staggering number of hotspots that O2 can, but they do offer some on the Underground (and a few overground) via the TFL network WiFi 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.

But apart from that you won’t benefit from the scheme anywhere else. If getting through all your data is a worry for you, Three offer some well priced unlimited data plans. Here’s the cheapest one:

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

Our verdict on free WiFi:

Win for O2

"O2 offer a very impressive network of WiFi hotspots, while Three’s scheme is restricted to the TFL network. O2’s scheme would be better if you could connect automatically to all their hotspots, but as it stands it’s much better than Three’s."

Compare pricing and deals

Perks and benefits: O2 vs Three

Inclusive roaming: O2 Travel vs Three Go Roam

Which network offers the better roaming scheme?

A globe with O2 and Three logos

O2 still include EU roaming on all plans

Free O2 EU roaming

See costs per country

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

Unlike the rest of the main UK networks (Three, EE and Vodafone) O2 have kept their inclusive EU roaming scheme in place (as have all these other networks). It’s still included on all of their plans.

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.

O2’s larger plans also come with an optional extra they call their “Travel Inclusive Zone”. This gets you an allowance of minutes, texts and data to use while roaming in these 27 non-EU locations.

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 no longer include roaming on their plans

Expired stampThree Feel At Home roaming

See what’s changed

(opens in new window)

We said above that O2 are the last main network to still offer EU roaming, which means that Three don’t offer it. If you signed up before October 2021 you’ll still get it, but if you take a new plan you’ll have to pay to roam in the EU.

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.

The cost is £2 per day in their EU destinations to use your regular minutes, texts and data. Beyond the EU it’s £5 a day, which adds up fast. And despite paying to access your allowance, your data usage will be limited to 20GB a month while abroad.

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

"Before Three changed their policy this would have been an easy win for Three. But now O2 are our number one pick for overall roaming (worldwide and EU) and the only one of the two to still offer inclusive EU roaming. An easy win for O2 here."

Compare pricing and deals

Extra benefits on O2 vs Three

Here are the other benefits O2 and Three offer to entice new customers

Giftbox with Three and O2 logos

O2 Priority helps get extra value out of your plan

O2 Priority rewards scheme

See available deals

(opens in new window)

You get access to O2’s popular rewards scheme they call “Priority” on every SIM only and phone contract. This gives you small extras for being an O2 customer, here’s what you can expect:

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).

Add on top of that the extra discounts on high-street food and shopping, online and travel services as well as the freebies they throw in from time to time such as free coffees and there’s even more to like with this scheme.

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

O2’s larger plans include Extras

Extras on O2

See all choices

(opens in new window)

O2 help customers on their pricier SIM only and phone contracts by offering free trials to certain entertainment services or other benefits that they called 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.

Once the trial is up you’ll start paying for the service, so make sure to cancel it if you don’t want that. You can also take O2’s Travel Inclusive Zone as an Extra, or any of the other ones from this list.

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 really don’t offer much extra

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.

While we’ve seen the results of that with the expansion of their 4G and 5G, it has come at the cost of most of Three’s benefits. They no longer include free roaming, data free streaming or little extras like their old easyJet upgrades.

Three do now offer a new rewards app they call Three+ which is similar to O2’s Priority. They recently offered pre-sale tickets for the Reading and Leeds festival, and usually offer discounts on high-street food, drink and shopping.

But Three’s deals tend to be a lot cheaper than O2’s, but as it stands you might be better off joining Three’s cheaper sub-brand SMARTY if you only want a SIM plan and don’t mind not having over-the-phone customer service.

Useful link: Read our SMARTY vs Three guide

Our verdict on extra perks

Win for O2

"Now that Three have got rid of most of their benefits, O2 take this category without much hassle. Three’s rewards app has room to grow, but for now it’s not quite as well established as O2’s Priority."

Compare pricing and deals

Comparing pricing and deals on O2 and Three

SIM only deals on Three and O2

Are Three a cheaper network than O2?

O2 and Three logos with a SIM card



1p Mobile logo
Three logo
ASDA logo
BT Mobile logo
Coop Mobile logo
EE logo
giffgaff logo
Honest logo
ID logo
IQ logo
Lebara logo
Lycamobile logo
O2 logo
Plusnet logo
Sky logo
Talkmobile logo
Tesco logo
Virgin Mobile logo
Vodafone logo
VOXI logo


Data: (0MB+)

Minutes: (0+)


Maximum length: (Any)

Added features

SIM only plan prices

A win for Three

"You’ll see using our SIM only comparison tool that Three’s deals tend to work out cheaper than O2’s for the same amount of minutes, texts and data and contract length. But it’s worth looking out for special offers that can narrow that gap."

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 O2 and Three

Do O2 or Three offer better phone contracts?

O2 and Three logos with smartphone icon

Phone options


Apple logo
Samsung logo
Alcatel logo
CAT logo
Doro logo
Emporia logo
Fairphone logo
Google logo
Honor logo
Huawei logo
IMO logo
Microsoft logo
Moto logo
Nokia logo
Nothing logo
OnePlus logo
Oppo logo
realme logo
Sony logo
TCL logo
Vivo logo
Xiaomi logo
OS box
Features box


Upfront: (Any upfront cost)

Monthly: (Any monthly cost)


Length: (6 - 36 months only)

Data: (Any)



Three logo
BT Mobile logo
EE logo
giffgaff logo
ID logo
O2 logo
Sky logo
Talkmobile logo
Tesco logo
Virgin Mobile logo
Vodafone logo
VOXI logo
Sort arrows Sort by lowest: Monthly cost | Upfront costTotal contract cost

Loading phone deals...

Loading wheel

O2 offer more flexibility with their phone contracts

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.

If you get your phone from O2 directly that means you’ll join on one of their Custom Plans (what they call Refresh). These split the cost of your phone and airtime plan (mins, texts, data) into separate finance agreements.

That gives you a great deal more flexibility as it lets you change the length and set an upfront fee that suits you. And no matter what combination you choose, the full cost for your device stays the same.

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.

O2’s offer their phones at pretty competitive prices. But their airtime plans are some of the priciest of all networks. But if you join on a shorter contract that can make O2’s phone deals fairly similar to Three’s if not cheaper.

Useful link: Use our phone contract comparison tool

Three offer more traditional phone contracts

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.

Three don’t base their contracts around finance like O2 do. That means you don’t have the flexibility to set contract lengths (they’re on 24-month contracts) or an upfront cost to suit you. And you can’t upgrade early.

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 imagine that since there’s no finance involved, passing a credit check for a Three phone deal might be a bit easier than passing one for O2, since they’re not essentially giving you a loan like a bank would.

Useful link: Use our phone contract comparison tool

Our verdict on phone contract prices:

Depends on what you want

"In terms of pricing, Three can work out a bit cheaper but the difference isn’t drastic. In terms of flexibility, O2 let you set your phone deal how you want. So your choice should really come down to if you care more about cost or flexibility, so it’s a draw here."

Compare phone prices

More guides about Three

Other O2 guides

Full network reviews