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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: 13th July 2023

What we compare in this guide

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Comparing O2 and Three's networks

Network coverage on O2 vs Three

We go over which network has better 2G/3G/4G/5G coverage

Mobile signal bars with O2 and Three logos

4G data is closer than ever, O2 still ahead for calls

Three network upgrades

See network upgrades

at Three.co.uk
(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.

Signal for calls and texts (2G/3G) is more widespread on O2 than on Three. It’s very rare to be somewhere with zero call signal on O2. On Three, there are still pockets of blackspots in rural locations.

But for 4G data (see 5G below), there’s now little to split them thanks to Three’s £2 billion network investments, ahead of their 3G phase out. Certainly in big cities and towns, you’re unlikely to notice differences.

We’d definitely recommend making use of both networks’ coverage checkers below, before writing either off. Check anywhere you can think you’ll regularly use your phone out and about, not just at home.

Useful link: Three’s Big Network Build latest

O2 are marginally ahead for 5G coverage

O2 best network for coverage banner

See latest awards

at O2.co.uk
(opens in new window)

Both O2 and Three have expanded their 5G networks massively. And both offer 5G on all their SIM only plans and 5G-ready phone contracts at no extra cost (check the 5G option in the checkout with O2).

O2 have 5G live in 750+ UK towns and cities while Three provide it in 484+ locations. And in our own tests, we’ve found coverage within those locations widespread. Historically only a few streets might have had it.

We will say that if you’re on the edge of a 5G coverage area on either, the quality of the connection does drop to often sub-4G quality. And that Three’s checker is more accurate about signal strength.

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:

Slight win for O2

"Despite the massive gains Three have made in coverage, statistically you are still likely to get better signal around the country on O2. The key is to research the places you’ll use your phone most before ruling out either.”

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Data speeds on Three vs O2

Do Three or O2 provide faster 4G/5G speeds?

O2 and Three logos with a speedometer icon

Three provide much faster 5G speeds

Three fastest 5G network banner

Why it’s faster…

at Three.co.uk
(opens in new window)

Three’s 5G speeds are much faster than the competition, including O2. They’ve achieved this by buying up more of the spectrum than the other networks, letting them use frequencies that are closer together.

They say they have the fastest 5G in the UK and results from Opensignal and Speedtest by Ookla confirm that. Three’s typical 5G speeds sit between 228.4 Mbps - 285.2 Mbps while O2 got between 80.57 Mbps - 92.3 Mbps.

Peak 5G speeds on Three can get up to a blistering 687.13 Mbps, while they can get up to a decent 214.2 Mbps on O2. Either way it’s much faster than what you’d get over home fibre optic broadband.

If you’re after bragging rights for the best possible speeds, then it’s hardly a competition, Three are by far the better choice. Still, O2’s 5G is an improvement over their 4G and will be good enough for most.

Useful link: Why Three say theirs is fastest

Three’s typical 4G speeds are also faster

O2 4G banner

What O2 say...

at O2.co.uk
(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’s results have shot up by a lot, with typical speeds of 30.7 Mbps putting them second place in Opensignal’s results. O2’s results have gone down to 16.8 Mbps, almost half as fast as Three.

In our real life testing of O2 we found speeds could go as high as 95 Mbps in the city centre but as low as 5 Mbps in rural areas. On Three we got up to 70 Mbps but only went as low as 7 Mbps. Three were more consistent.

So while you might be able to get faster peak speeds on O2, that’s only really possible in the city centre. Anywhere else you’ll typically get more consistently good 4G speeds on Three.

Useful link: Three carry more data than any other network

Our verdict on data speeds:

A win for Three

"Three knock it out of the park with their 5G speeds and are much better for typical 4G speeds. O2 can potentially give you faster peak 4G, but otherwise they can hardly compete with Three on speeds."

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WiFi calling on O2 vs Three

You get WiFi calling on Three and O2, so which scheme is better?

WiFi calling symbol with O2 and Three logos

Three’s WiFi calling scheme is better than O2’s

Three WiFi calling

See Three's scheme

at Three.co.uk
(opens in new window)

Both WiFi calling and 4G calling (VoLTE) are standard features on O2 and Three and let you connect to calls using WiFi and 4G signal. This helps eliminate blackspots indoors and many other places signal can’t reach.

You can send SMS texts over WiFi and 4G on both networks 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?

Most iPhone models are supported for WiFi calling on both, but O2 don’t support as many Android models. And phones bought elsewhere should work with Three’s WiFi calling, while O2 are more defensive about this.

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 issues with them.

Useful link: See Three’s guide to WiFi calling

Our verdict on WiFi calling:

Slight win for Three

"Three and O2 have very similar WiFi calling schemes in terms of how they work, but it’s easier to get it working on older Androids with Three. So Three just take this one."

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WiFi hotspots on Three vs O2

Do O2 or Three provide more WiFi hotspots around the country?

WiFi symbol with O2 and Three logos

O2 provide loads of WiFi hotspots around the UK

Free O2 WiFi hotspots

Find nearby hotspots

at O2.co.uk
(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.

O2 offer one of the best schemes of all networks. With the O2 WiFi hotspot scheme you get access to 15,000+ hotspots in populated places like transport hubs, shops and other venues.

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.

It’s a handy scheme for saving data on the go. And if you’re a regular traveller on the London Underground then you’ll love the free WiFi you get on the TFL network on O2.

Useful link: Find hotspots near you

Three offer 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.

So you can keep yourself connected at Underground stations and platforms, but not in the trains themselves. You get it on pay monthly and on Pay As You Go, you just need to activate it as an add-on.

But you don’t get any free hotspots around the county like you do on O2. 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 provide more hotspots than Three and in more places. The only potential downside is that they don’t all automatically log you in, but at least you’re actually getting more hotspots anyway. O2 win this one easily."

Compare pricing and deals

Perks and benefits: O2 vs Three

Inclusive roaming: O2 Travel vs Three Go Roam

Which network is better for going abroad?

A globe with O2 and Three logos

O2 still offer inclusive EU roaming as standard

Free O2 EU roaming

See costs per country

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

While the other main UK networks (Three, Vodafone, EE) have removed inclusive EU roaming from their plans, O2 have kept theirs in place (along with all these networks). Roaming in the EU costs nothing extra on O2.

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 you can get their “Travel Inclusive Zone” benefit on their higher end plans. This lets you roam beyond the EU in these 27 worldwide locations with a small allowance of minutes, texts and full-speed data.

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 include roaming on premium plans

Three Feel At Home roaming

See what’s changed

at Three.co.uk
(opens in new window)

As we said above, Three are one of the main UK networks to remove inclusive EU roaming as a standard feature. But you can roam in these 71 EU and worldwide countries on Three’s higher end Premium and Plus plans.

You get a different number of daily roaming passes to use per year depending on which plan you take and how long your contract is. You’ll get twice as many on a Premium plan as you would on a Plus plan.

But you’ll still be limited to 12GB while abroad, even though you’re paying a premium price to roam. And when you run out of passes you’ll pay £2 a day to roam in the EU or £5 a day beyond the EU.

So if you want to roam in the EU often you might be better off joining Three’s cheaper sub-brand SMARTY offer inclusive EU roaming as standard. But Three can be a good option for worldwide roaming.

Useful link: Full guide to roaming on Three

Our verdict on inclusive roaming

A win for O2

"Three’s roaming scheme has improved, but the fact that you don’t get inclusive EU roaming on every plan like you do on O2 makes them the worse option for going to the continent. Both are decent options for worldwide roaming, however."

Compare pricing and deals

Extra benefits on O2 vs Three

We go over what else Three and O2 offer their customers

Giftbox with Three and O2 logos

O2 Priority gets you special offers to use in real life

O2 Priority rewards scheme

See available deals

at O2.co.uk
(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:

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).

And you’ll also get special offers on high-street food, drinks and shopping, online and travel services and a few freebies such as free coffees now and again. That can give you extra value out of your plan.

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 include Extras on their premium plans

Extras on O2

See all choices

at O2.co.uk
(opens in new window)

O2 give you some nice extra benefits on their higher end SIM only and phone contracts such as free trials to entertainment services and more that they call 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.

If you were going to join on a longer, more expensive plan on O2 anyway then you can get some genuinely nice value with these benefits. But it’s still best to join on a plan that suits your needs.

Useful link: Full O2 Extras FAQs

Three have a new rewards app

Three Plus rewards app banner

See the benefits

at Three.co.uk
(opens in new window)

Three introduced their Three+ rewards app a little while ago and it works very similarly to O2 Priority. You’ll get special offers on food and drink as well as shopping and other services.

And you’ll also get first dibs on tickets to events hosted at venues owned or sponsored by Three. That includes the Leeds and Reading festivals amongst others.

You get access to the app on any of Three’s pay monthly or Pay As You Go deals. It’s a great way to get extra value on top of your plan, especially since Three are a lower cost network than O2 in the first place.

We still think this app has some space to grow and the list of services you can get special offers for is still a bit limited. But it’s a genuinely great scheme and a nice benefit for joining them.

Useful link: Our guide to the best customer reward schemes

Three’s Plus and Premium plans offer extra perks

A phone with images of benefits surrounding

Read their guide

at Three.co.uk
(opens in new window)

We mentioned Three’s Plus and Premium plans above when talking about their roaming. But not only do you get worldwide roaming passes on these plans, but you’ll also get some other smaller benefits.

On a Plus phone contract you’ll get a three year extended warranty on your device, which is good if you’re a bit of a butterfingers. And you’ll get a free trial to Paramount+ for half of your contract.

Their Premium plans are higher in price but give you a free screen repair if you take a 24-month contract as well as a Paramount+ subscription that lasts the entire length of your contract.

On SIM only, you’ll get the same but without the extended warranty or screen repair, as this type of deal do not include a phone.

There’s nothing earth shattering here, but these can add a bit of extra value on your contract. And of course you get them alongside your roaming passes, so these plans can be genuinely good choices.

Useful link: Three’s guide to their Plus and Premium plans

Our verdict on extra perks

Win for O2

"Three have added a bit more in terms of added benefits, so this one is a lot closer now. But O2’s rewards app is just a bit better and their Extras are a bit more flexible than Three’s. But you might prefer one or the other."

Compare pricing and deals

Comparing pricing and deals on O2 and Three

SIM only deals on Three and O2

Which network offers the better value SIM only deals?

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SIM only plan prices

A win for Three

"Three’s deals tend to work out quite a bit cheaper than O2’s for the same amount of mins, texts and data. But it’s worth keeping an eye out for special offers on either network to find the best deal for you."

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Special offers available on O2 and Three

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

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Phone contracts compared on O2 and Three

Which network offers more flexibility and better prices on their phone deals?

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O2 offer more flexible phone contracts

O2 custom plans

See custom plans

at O2.co.uk
(opens in new window)

You can either take an O2 phone contract directly from their website directly (which we go over below) or join via a third party reseller. You’ll find cheaper deals as they buy phones in bulk (compare prices here).

Taking a phone from O2 directly 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.

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. The overall cost of your device will be the same no matter what you choose.

And you can pay off your phone early if you want and upgrade to a new device. Overall, O2’s phone contracts are quite good value, but their usage plans (mins, texts, data) do bring up the cost quite a bit.

Useful link: Use our phone contract comparison tool

Three’s phone contracts are quite flexible

Compare phone contract prices

Use phone deal finder

at simsherpa.com
(opens in new window)

You can also join a Three phone contract via a third party reseller for a cheaper price or you can take one directly from their website or stores. Use our comparison tool to find the best price here.

Three’s contracts work similarly to O2’s where the cost of your device and usage plan are on separate finance agreements. You can choose to pay off your phone over 12, 24 or 36 months.

And you can pay the whole cost of your phone whenever, if you want to upgrade, and set an upfront cost how you like it. The overall cost of your device will stay the same no matter what you choose.

They tend to be quite good on price and they already beat O2 in terms of their usage plan (mins, texts, data) costs. But use our comparison tool here to find the best possible deal for the phone you want.

Useful link: Use our phone contract comparison tool

Our verdict on phone contract prices:

Depends on what you want

"There really isn’t a massive difference in the cost of devices, but Three’s cheaper usage plans can make them the better option. But O2 offer a little bit more flexibility in how you set up your plan. It comes down to what you prefer ultimately."

Compare phone prices

More guides about Three

Other O2 guides

Full network reviews