O2 vs Three Mobile: which is better?

Last updated: 8 September 2021   By Dr Lucy Brown, Editor

O2 and Three are two of the leading mobile providers in the UK, providing a full range of services to customers.

three mobile logo on wall
Credit: Lloyd Carr/Shutterstock.com

At a glance

O2 Three
Price of contract £10 - £30 £9 - £32
Length of contract 30 days - 36 months 30 days - 24 months
Speeds Average 15.4 Mbps Average 10.5 Mbps
Unlimited data? No - Max 50GB Yes
Coverage (population) 99% 99%
Customer satisfaction 92% 89%

Special offers

O2 and Three both run special offers from time to time. Here's a quick look at their latest deals.

Offer Terms

150GB Plus data, unlimited minutes and texts and Amazon Prime or Disney+ free for 6 months just £19.99/mth

Hurry! Offer ends 5 June 2024

24 month contract. Mobile SIM only.

Unlimited Plus data, unlimited minutes and texts and Amazon Prime or Disney+ free for 6 months just £16.50 for the first 6 months

Hurry! Offer ends 5 June 2024

24 month contract. Mobile SIM only. £32.99/mth after 6 months.

Offer Terms

3 months free on all 24 month SIM only plans from just £9/mth.

24 month contract applies. SIM only for mobile.

Call plans

Winner: Three win for both pay as you go and monthly contracts, mainly due to the data allowances available.

O2 and Three offer a full range of pay monthly SIM only deals, pay as you go (PAYG) plans and handsets on contract.

Let's look at those different plans in turn.

Pay monthly

Winner: Three provide more data for lower monthly costs.

Traditional pay monthly SIM deals on a contract are available for 24 months, 12 months or 30 days on both O2 and Three, meaning both offer great flexibility to SIM only customers.

Here are some examples of their 24-month and 12-month deals:

Package Minutes Data Contract term Monthly price
Three 4GB data Unlimited 4GB 24 months £9
O2 5GB data Unlimited 5GB 24 months £10
Three 30GB data Unlimited 30GB 24 months £14
O2 20GB data Unlimited 20GB 24 months £15
Three 30GB data Unlimited 30GB 12 months £15
O2 20GB data Unlimited 20GB 12 months £18
Three Unlimited data Unlimited Unlimited 12 months £20
O2 Unlimited data Unlimited Unlimited 12 months £33

While O2 is only slightly more expensive on lower data plans, it's when we get as high as unlimited SIM only deals that Three show markedly better value for money.

Here are some 30-day deals:

Package Minutes Data Contract term Monthly price
Three 4GB data Unlimited 4GB 1 month £16
O2 3GB data Unlimited 3GB 1 month £18
Three 30GB data Unlimited 30GB 1 month £24
O2 25GB data Unlimited 25GB 1 month £25
Three Unlimited data Unlimited Unlimited 1 month £26
O2 Unlimited data Unlimited Unlimited 1 month £36

Again, the gap widens as the data plans grow, leaving Three as the undisputed leader when it comes to value for money.

Even the fact that Three have scrapped their popular Go Binge service that zero-rated certain streaming services doesn't seem to matter as much when their unlimited data deals are so cheap in comparison to O2's.

However, something O2 do offer extras and perks that Three simply don't match.

For example, all customers receive daily offers through O2 Priority and those taking longer SIM only and handset contracts will be able to access an Extra for free for up to 12 months.

If it's a service that customers are interested in, this might make up for the extra monthly fees - although watch out to see if it's truly worth it.

Learn more about the facts behind data allowance headlines or check out the cheapest SIM only deals.

Pay as you go

Winner: Three is cheaper and offers higher data allowances.

Both O2 and Three have switched to a pay as you go (PAYG) bundle approach, with O2 confirming back in November 2019 that they were scrapping traditional PAYG.

Instead, customers on both networks now purchase a specific amount of data, minutes and texts at one time and they have access to it for 30 days.

The major difference between the two providers is that O2 allow data to rollover from one month to the next while Three customers will lose whatever they don't use.

Here are their PAYG deals side-by-side:

Package Minutes Data Contract term Monthly price
Three 12GB data PAYG Unlimited 12GB PAYG £10
O2 7GB data Unlimited 7GB PAYG £10
Three 30GB data PAYG Unlimited 30GB PAYG £15
O2 £15 data Unlimited 15GB PAYG £15
Three 50GB data PAYG Unlimited 50GB PAYG £20
O2 30GB data Unlimited 30GB PAYG £20
O2 100GB data Unlimited 100GB PAYG £30
Three Unlimited data PAYG Unlimited Unlimited PAYG £35

It's notable that O2 don't offer an unlimited option on PAYG. Plus, their data allowances are lower than Three's at every level, making Three a more economical option for PAYG customers.

Note: O2's £10, £15 and £20 allow a customer's full allowance to be rolled over while the £30 bundle allows rollover of up to 100GB. However, if customers don't renew their pack on the same day the previous one expires, there will be no data rollover.


Winner: Three offer inclusive roaming to more countries under their Go Roam Around the World service.

O2 tightened their European roaming rules following Brexit, with customers now able to use a maximum of 25GB for free while roaming.

This is better than EE and Vodafone who have both introduced daily fees for customers to use their phone in Europe.

It's also now better than Three's allowance of 12GB, although that allowance is usable in 71 destinations under their Go Roam Around the World service.

Customers who want to undertake more data-heavy tasks may be better served by a Data Passport at £5 per day, but that isn't obligatory and customers can make do with up to 12GB of roaming data on their normal tariff.

Meanwhile, O2 offer O2 Travel for countries outside the Europe Zone. This costs £4.99 per day for 120 minutes, 120 texts and data.

This is also included as an inclusive bolt-on with some O2 Refresh and SIM only tariffs so keep an eye on the small print in deals if that's an important feature.


Winner: Three beats O2 on price most of the time, plus their contract pricing structure is simpler than O2's.

Both O2 and Three offer a range of handsets from the basic models like up to the latest iPhone and Samsung phones.

O2 provide separate costings for handsets, so customers can understand how much they're paying for the device and how much they're paying for airtime every month.

Let's see how O2 and Three compare on three popular handsets with unlimited data:

Handset Minutes Data Initial price Monthly price
O2 Apple iPhone 12 (64GB) Unlimited Unlimited £30 £56.16
24 month term
Three Apple iPhone 12 (64GB) Unlimited Unlimited £49 £54
24 month term
O2 OnePlus Nord 2 5g (128GB) Unlimited Unlimited £10 £50.48
24 month term
Three OnePlus Nord 2 5g (128GB) Unlimited Unlimited £19 £39
24 month term
O2 Oppo Find X3 Neo 5G (256GB) Unlimited Unlimited £20 £56
24 month term
Three Oppo Find X3 Neo 5G (256GB) Unlimited Unlimited £19 £45
24 month term

Note: O2 contracts usually default to 36 months but customers can choose shorter periods if they want to pay more per month or more upfront.

As we can see from the table, Three is slightly cheaper across all our test handsets taking into account their 24-month standard deals.

Special offers will vary from handset to handset, but Three are likely to be slightly cheaper than O2 on most models.

However, price isn't everything, so let's take a closer look at some pivotal issues: coverage and speed.


Winner: Tie: it depends which part of the UK we're in and local factors play a role too.

The most recent Ofcom Connected Nations Report for 2020 found that coverage of 4G services continues to improve, with 99% of indoor premises and 91% of geographical locations being served by at least one of the major operators.

Drilling down into that, we can find that the 95% of all indoor premises have access to O2 4G services, while the figure for Three is lower at 90%.

On geographical measures, O2 reach 80% of the UK with their 4G service, while the corresponding figure for Three is 79%.

These figures demonstrate that O2's coverage is better than Three's, yet that doesn't mean that will necessarily be the case in a customer's area as we explain more fully in guide to mobile coverage across the UK.

A quick look at coverage across the four countries of the UK demonstrates what we mean:

So, while O2 have better coverage in Scotland, Three has the edge in Wales and Northern Ireland.

Boosting 4G coverage in rural areas is a high priority for the Government (and, therefore, mobile networks too).

O2 and Three are signed up to the Shared Rural Network (SRN) agreement meaning they will share over 200 new masts to be built by 2024.

This will improve rural coverage for customers of both networks while, individually, they continue to boost their 4G coverage and signal strength at sites across the UK.


Winner: O2 5G is active is more towns and cities.

The 5G rollout hasn't been extensively covered by regulator Ofcom yet, so it's difficult to objectively say which network is doing it better.

O2 say their 5G services are available in parts of 194 towns and cities across the country, while Three's latest update says they have 300 sites in over 100 places.

This distinction is important because Three is upfront about the fact that they have no more than a handful of 5G sites in their 5G areas.

The 5G rollout is going to take time, meaning customers with 5G-capable handsets may enjoy coverage in some busy areas they visit regularly but not in other places where there isn't yet demand for 5G speeds.

For now, 5G coverage may be considered a nice-to-have by customers comparing Three and O2 but not a deal-breaker.


Winner: Three are shown in recent research as having faster 4G speeds than O2.

Speed is a key component of a reliable mobile phone service, with both operators competing on 4G and 5G technologies.

If we look at research from Opensignal published in April 2021, we can see the average download and upload speeds experienced by customers are not that different:

O2 Three
Download Speed Experience 17.3Mbps 19.3Mbps
Upload Speed Experience 6.7Mbps 6.8Mbps

Data published by RootMetrics looking at the second half of 2020 had a similar story on download speeds:

O2 Three
UK-wide speeds 12.9Mbps 13.9Mbps

Both of these reports show Three slightly ahead on download speed, something that goes against the popular opinion that Three is the slower network.

On a nation-by-nation analysis, the RootMetrics research shows Three ahead in Scotland, Wales and England:

O2 Three
Scotland 11.5Mbps 13.4Mbps
Northern Ireland 12.4Mbps 11.0Mbps
Wales 7.0Mbps 11.6Mbps
England 13.3Mbps 14.1Mbps

So, in most cases, Three is going to be the faster network, yet most customers probably won't notice the slight uptick in speeds and, as we've pointed out above, coverage plays a big part in this too.

Data on 5G speeds from RootMetrics shows that both networks are improving their speeds. RootMetrics test signal in 16 major cities, so the data shouldn't be taken too far out of context, but it's a good show of progress.

Here are some comparisons between H1 2021 and H2 2020:

O2 Three
Cities with median 5G speeds over 150Mbps 6 0
Cities with median 5G speeds between 100Mbps and 150Mbps 10 6
Cities with median 5G speeds between 50Mbps and 100Mbps 0 10

From this research, then, it looks as though O2's 5G is now delivering consistently higher speeds than Three's, albeit only in a handful of test cities so far.

Customer service

Winner: O2 has a better customer service record than Three.

With some of our comparisons, customer service is where the differences really start to show and it's O2 who have the edge in this battle.

These are figures from Ofcom's most recent Comparing Service Report:

O2 Three Industry Average
Satisfaction with Overall Service 91% 86% 90%
Satisfaction with Value for Money 79% 88% 83%
Call Waiting Time 2m 17s 1m 3s 2m 7s
Customers with a Reason to Complain 7% 13% 10%
Complaints per 100,000 Customers 8 23 13
Satisfaction with Complaint Handling 62% 56% 57%

O2 posts scores better than the industry average in several key areas including overall satisfaction and satisfaction with complaints handling.

Three answered the phone a little quicker, however, and far more customers thought they represented good value for money.

On balance, though, if customer service is a crucial consideration, O2 nudge Three out of the way to triumph.

Verdict: Who is best O2 vs Three?

Overall winner: Three have the edge, even though O2 beat them on some points.

Compare deals

If data value on the top handsets and on SIM only deals is important, Three win. Their pay monthly plans, PAYG tariffs and handset deals are cheaper than O2's and offer higher data allowances too.

In terms of coverage and 4G speeds, Three also win this battle, although O2 are showing faster progress on 5G services.

O2 start to shine when we think of them as more of a premium mobile network.

For example, they offer an Extra to many customers and automatic access to O2 Priority for special deals too. In addition, their customer service metrics are better than Three's, with far fewer O2 customers saying they have a reason to complain about their mobile service.

Ultimately, it might come down to which network has a special deal on the handset a customer is looking at. When using the free Choose tool to compare mobile deals, sort by special offers to see the best deals available from each network.


Find the best deal on a new handset

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