O2 vs Three: how the two networks compare

O2 and Three run separate networks and don't share masts with each other, so the signal you get can differ between them. O2 is owned by Virgin Media O2. Three is part of VodafoneThree, the group formed by its merger with Vodafone, and its customers can use Vodafone's masts at sites where the two networks share them. Beyond coverage, the two part ways on 5G speed, roaming, perks and how their prices rise each April.

How do O2 and Three compare at a glance?

The table pulls prices and price rises from our live deal feed, so it matches the deals on our comparison pages today. The roaming, eSIM and exit-fee rows come from each network's own pages.

Which has better coverage?

Each leads on something different. Ofcom's January 2026 figures put O2 well ahead on outdoor 5G, reaching 86.2% of premises against Three's 75.9%. Three edges indoor 4G, at 96.6% of premises against O2's 95.5%, and indoors in rural areas, at 85.0% against 82.0%. Outdoor 4G is near-universal on both.

Three customers also gain from mast sharing with Vodafone. The group says sharing was live at more than 10,000 mast sites by May 2026, with the full rollout expected around 2033. Ofcom still reports the networks separately, so the figures above don't include it. O2 has no equivalent arrangement.

National figures only tell you so much. Check your postcode, and the places you travel to, on our mobile coverage map.

Which has the faster 5G?

Independent testing has gone Three's way. According to Ookla's Speedtest Awards for the second half of 2025, Three had the UK's fastest 5G download speeds, its sixth win in a row, and Opensignal's January 2026 report also placed it first. The same Ookla awards named O2 the slowest of the four networks for 5G.

Speed and reach are different things. O2's 5G reaches more homes; Three's is quicker where it exists. If you mostly use 5G in a city centre, Three's lead matters more. If you want 5G in more places, O2's footprint matters more.

Which is cheaper, O2 or Three?

For unlimited data on a two-year contract they were close when we checked on 17 October 2026. Three's cheapest was £22 a month, rising to £24.30 in April 2027 and £26.60 in April 2028, which comes to £583.20 over the contract. O2's was £23 a month, rising to £25.50 and then £28, or £612 in total.

One difference sits in the small print. Three's unlimited SIM only plans list "speeds up to 100Mbps" on its own page. O2 publishes no equivalent cap on its unlimited plans. For most phone use 100Mbps is plenty, but it's worth knowing if you tether a laptop or download large files.

Our comparison carries Three's SIM plans on 12 and 24-month terms, and O2's on 30-day, 12 and 24-month terms. O2's 30-day unlimited plan was £38 a month when we checked, and its cheapest plan overall was £7 a month for 10GB. Three's cheapest plan was £6 a month for 1GB on 24 months. Our data allowance guide covers how much you need.

Can the price go up during the contract?

Yes, on both, and both set the amount out in pounds and pence before you sign. O2's price guide says: "Each April, your airtime plan will increase by £2.50 for voice plans and 75p for data-only and smartwatch plans". Three's rise varies by deal; the deals in our feed carry rises of £1.80 to £2.30 a month each April, which is why the table shows a range.

Over a two-year contract that's two rises on either network. Our price rise guide explains the rules and which networks don't raise prices at all.

Which is better for using your phone abroad?

Roaming is one of the clearest differences. O2 includes EU roaming up to 25GB a month with no daily fee, the only one of the big networks to do so. Three charges £2.75 a day for customers who joined from 18 December 2025, with roaming included or daily passes bundled on its Value and Complete plans, and not on its Lite plans. Three caps roaming data at 12GB a month under its fair-use policy.

A week in Spain costs nothing extra with O2 and £19.25 on a Three plan paying the daily charge, based on the prices each publishes. Three's Go Roam does cover more than 160 destinations worldwide, which matters if you travel beyond Europe. Our EU roaming guide covers every network's terms.

What perks and family discounts come with each?

O2's main perk is Priority, a free rewards app with weekly offers from brands such as Greggs, cinema deals and 48-hour ticket presales. It's open to every O2 customer, including pay as you go. For families, Multisave takes 20% off the airtime of each extra eligible line, up to 20 numbers. The first line isn't discounted.

Three's equivalent is Three+, a free rewards app for pay monthly and pay as you go customers aged 18 or over, with partner offers and ticket presales. Three doesn't currently publish a multi-line discount on its site, so if you're putting several lines on one account, O2 is the one with a stated discount.

Will either run a credit check?

Three says it will: "When you sign up for a Pay Monthly plan, we'll run a credit check." O2's pay monthly plans are contracts too, so check its terms before you apply if a credit check concerns you.

How do their customer service records compare?

Ofcom's figures for January to March 2026 recorded 2 complaints per 100,000 Three customers and 3 for O2, against an industry average of 2. Ofcom treats both figures as comparable with the average, so a one-point gap isn't a meaningful difference.

Ofcom's 2024 customer service survey scored them close for overall satisfaction: 87% for Three and 85% for O2, against an 88% average. The clearest gap was the phone queue. Average call waiting time was 46 seconds at Three and 3 minutes 27 seconds at O2. Three's phone line runs 8am to 8pm on weekdays and 9am to 6pm at weekends. O2 has shops across the country as well as a phone line.

Why you might choose O2

• You travel in Europe and want roaming included without a daily fee.
• Outdoor 5G coverage in more places matters more to you than peak speed.
• You want a 30-day unlimited plan.
• You'd use Priority, or add lines through Multisave.

Why you might choose Three

• You want the fastest 5G speeds in independent tests, and 5G where you live is already good.
• Indoor coverage, especially in rural areas, matters most to you.
• You'd benefit from Vodafone's masts at shared sites near you.
• You travel beyond Europe and would use Go Roam's wider list of destinations.

How do you switch between O2 and Three?

This switch changes your network, so check coverage at home and work first. To keep your number, text PAC to 65075 from your current phone. The code arrives within a minute, and your new network completes the switch within one working day under Ofcom's rules. Our switching guide covers each step.

Leaving early costs an exit fee on both. O2 charges the airtime left, less 4%, and Three charges the payments left, less 3%. Our mobile exit fee calculator works out either.

Sources used

Prices, contract lengths and scheduled rises come from our live deal feed and refresh whenever the site updates. Everything else comes from the sources below, read on the dates shown.

• O2, read 23 September 2026: price guide and Multisave pages.
• Three, read 17 October 2026: unlimited data, Go Roam and credit check pages.
• Vodafone: its network sharing explainer, for the mast sharing figures.
• Ofcom: the Connected Nations Spring 2026 update for coverage, telecoms complaints data for January to March 2026, and the Comparing Customer Service report for 2024.
• Speed tests: Ookla's Speedtest Awards for the second half of 2025, and Opensignal's January 2026 report.