O2 SIM Only Deals Explained: Which Plan is Right for You in 2026

Step outside that zone and O2 roaming costs extra, unless your Plus or Ultimate plan covers the destination. That is where a travel eSIM can help, and HelloRoam has plans for 185+ destinations.

O2 SIM only deals at a glance

• Contract lengths: 30-day Mini plans, or Classic, Plus and Ultimate plans on 12 or 24 months.
• Prices on O2's site: from £18 a month on 24 months, £21 on 12 months and £24 on 30 days, all for 3GB.
• Price rises: every plan goes up by £2.50 each April.
• Included on every plan: unlimited UK minutes and texts, 5G at no extra cost and Europe Zone roaming up to 25GB.
• Plus and Ultimate extras: data rollover, plus roaming in 27 (Plus) or 75 (Ultimate) destinations outside Europe.
• Cheaper routes: O2 deals on comparison sites, and resellers on O2's network such as giffgaff, can cost far less than O2's own page.

O2 SIM only plans and prices on O2's own site

We checked O2's SIM only page on 01/10/2026, and it listed 29 plans. A 30-day Mini plan costs £3 a month more than a 12-month Classic plan with the same data, and 24 months costs less again:

On 12 months, Plus plans cost £1.99 a month more than Classic and Ultimate plans £6.99 more. Plus adds data rollover and roaming in 27 destinations outside Europe, such as the USA and Australia. Ultimate stretches that to 75 destinations and adds O2 Satellite. O2 also runs short offers on some 24-month plans, each with an end date on the page.

giffgaff and Tesco Mobile are MVNOs (mobile virtual network operators), carriers that resell O2's network. Their pricing can undercut O2 direct by a wide margin, as the giffgaff example below shows, though O2's own extras don't come with them.

O2 Priority is open to every O2 mobile customer aged 16+, on any plan, and to Virgin Media broadband customers. Its perks include a Greggs hot drink or savoury treat for £1 each week, four Vue cinema tickets for £18 a month and 48-hour ticket presales. They are discounts from partners, not money off your O2 bill.

For anyone unwilling to commit to even a 30-day contract, O2 Pay As You Go remains an option. Its Rolling plans have no minimum period, but they take a monthly payment automatically by card. Big Bundles run on top-ups instead.

O2 5G SIM only: coverage and what you need

O2 includes 5G on every SIM only tier at no extra charge. There's no premium band to unlock or bolt-on to buy, but four things have to line up before your phone shows 5G.

What you need to access O2 5G:

1. A 5G-ready handset. An older 4G phone on an O2 SIM won't gain 5G, so check your handset spec before committing.
2. An active O2 SIM only plan. Any tier qualifies automatically. No upgrade or add-on required.
3. 5G switched on in your phone's settings. O2 says 5G must be enabled on the device, so check this if a new SIM still shows 4G.
4. 5G signal at your location. Coverage varies by postcode, and O2's coverage checker lets you check yours.

Step off a train at Manchester Piccadilly or out of a Birmingham shopping centre and your phone's status bar shows exactly what the network's delivering. That bar tells the real story.

O2 says its 5G covers thousands of towns and cities across the UK. Where 5G isn't available, your phone switches to 4G, which O2 says reaches 99% of the UK population. The handoff happens quietly, with no input needed from you.

That 99% counts people, not land, and O2 admits the gaps: O2 Satellite exists to cover areas its network didn't reach. It comes with Ultimate plans, or as a bolt-on on Pay Monthly contracts, and needs a compatible phone.

Where to find the cheapest O2 SIM only deal

The cheapest O2 SIM only deal we found was £7 a month for 10GB, listed on Uswitch's O2 SIM only page on 03/10/2026 on both a 12-month and a 1-month contract. On the 12-month contract, it rises by £2.50 each April, starting in April 2027. The same list had 50GB for £8 a month, while O2's own site started at £18 a month for 3GB on 24 months.

The cheapest way onto O2's network isn't always through O2. MVNOs like giffgaff run on O2's network, and giffgaff's monthly rolling plan gave 20GB for £10 on the same day, against £27 for 20GB on O2's own 30-day plan. If raw monthly cost is your only criterion, compare reseller rates alongside O2's own plans before you commit.

On O2's own page, a 30-day plan's higher price buys flexibility: useful if a fortnight in Southeast Asia or a month in Europe is on the horizon and you'd rather not be locked in before sorting out travel data. If you're staying put, 24 months is the cheapest per month there.

Uswitch shows when it last updated its deal list and says it may earn commission from the companies it refers you to. Deals rotate, so treat any figure here as a snapshot and read the April rise in the price details before you buy.

Choosing an O2 SIM only contract length

Three contract lengths cover most decisions. On O2's own page, 24 months has the lowest monthly price: 20GB on Classic costs £21, against £24 on 12 months and £27 on a 30-day Mini plan. 30-day rolling suits the uncommitted, the frequent traveller, or anyone eyeing a phone upgrade within the year.

30-day rolling

The monthly cost runs £3 higher than a 12-month contract, but you can leave with 30 days' notice. That flexibility matters if you're expecting a better deal to land soon, planning a handset upgrade, or spending significant time abroad where your UK data allowance barely gets touched. Frequent travellers who rely on a no-contract travel eSIM for data overseas often find a lower-cost rolling plan makes more sense than a high-data fixed contract they won't fully use.

12-month: the middle ground

Twelve months is the middle ground. On Classic, the rate is £3 a month lower than a 30-day plan and at least £3 higher than 24 months, and the commitment is short enough that you're not locked in if the market shifts. Prices also differ by where you buy, as the gap between O2's own page and the O2 deals on Uswitch shows.

24-month: the lowest monthly price

Two years with any provider is a real commitment, and your price still rises by £2.50 each April along the way. In return, O2's 24-month plans are its cheapest per month, and the tiers overlap: 100GB cost £26.99 on both Plus and Ultimate, and Unlimited cost £29.99 on Ultimate against £33.99 on Plus.

One detail worth knowing: when a fixed term ends, O2 doesn't start a new one. The agreement simply carries on until you end it, and the £2.50 April rise still applies. Setting a calendar reminder a month before the end date takes a moment and gives you time to compare deals.

If you're on an O2 phone contract, O2 says it lowers your bill automatically once your device is paid off. Compare that lower bill with the SIM only prices above before you switch.

Using your O2 SIM abroad: Europe Zone and beyond

Yes, and Europe costs nothing extra on O2. O2 includes roaming in its Europe Zone on Pay Monthly and Pay As You Go: your UK minutes, texts and data work as they do at home, with a 25GB limit if your UK data allowance is bigger. The zone covers 48 destinations, including Switzerland, Norway and Iceland, and O2 says it is the only major UK network to include Europe Zone roaming in its tariffs.

The catch is where O2's Europe ends. Turkey isn't in the Europe Zone, and neither are Andorra, Serbia or Morocco, so a trip there follows O2's rules for the rest of the world.

O2's Europe offer does stand out among the big networks. EE charges £2.72 a day in its EU zone, or £16.50 for a 7-day pass, and lists EU roaming as one of its Inclusive Extras. Vodafone sells 8-day (£16) and 15-day (£21) European roaming passes to Pay Monthly customers whose plans don't include Europe. Three's Lite and older Advanced plans need a Go Roam pass or a daily charge.

Outside Europe, your plan decides the cost. Plus plans include roaming in 27 more destinations, including the USA, Canada and Australia, and Ultimate plans in 75, both with data capped at 2Mbps. Where your plan doesn't cover a destination, O2 Travel costs Pay Monthly customers £7 a day in 75 destinations outside Europe, charged only on days you use your phone, and Data Roaming Bolt Ons sell data in any country. Pay As You Go customers can't use O2 Travel or Data Roaming Bolt Ons, so check O2's rates for your destination before you go. O2 says to check its destination guide, or look out for its texts when you land.

On a Classic plan, ten days in Turkey using O2 Travel every day costs £70, or you could buy a 5GB data bolt-on for £29 and pay for calls separately. Morocco sits in O2's priciest bolt-on zone, where 1GB costs £65 and calls cost £3 a minute to make or receive.

Common pitfall: Checking O2's coverage map and assuming coverage equals cost-free data. Coverage and cost sit on the same page but are not the same figure.

When a travel eSIM makes more sense than O2 roaming

An eSIM (a digital SIM profile, usually installed from a QR code) sits alongside your physical O2 SIM on a phone that supports eSIM, without touching the SIM tray. You don't need to choose between your UK number and a local data plan abroad.

Leave the O2 SIM active for bank authentication texts and two-factor login codes on your UK number, and let the travel eSIM handle data. Keep calls in mind: outside Europe, O2 charges £3 a minute to make or receive them unless your plan or O2 Travel covers calls. Bank texts matter more abroad than most people expect: a card security block mid-trip is a specific kind of disruption that arrives at inconvenient moments, often at dinner.

Inside O2's Europe Zone, most O2 customers don't need one, because the UK allowance already works there up to 25GB. Outside it, HelloRoam connects to 212+ networks worldwide and includes 24/7 support with its plans. That last point matters when you're troubleshooting a connection across a time-zone difference. We sell travel eSIMs, and our conflict of interest policy explains how we write about them.

One honest counterpoint: in the Europe Zone, or on a Plus or Ultimate plan whose inclusive zone covers your destination, O2 alone will usually do. A travel eSIM earns its place where O2 charges most, such as Morocco, where an O2 data bolt-on costs £65 per gigabyte and Morocco eSIM plans are the alternative.

To check your phone, O2 says to dial *#06#: if you see an EID, it supports eSIM. Our list of eSIM compatible phones covers the main models, and iPhone owners can follow our eSIM guide for iPhone travellers.

What you get for O2's higher SIM only prices

O2 doesn't say why its prices sit where they do. What it does say is that it runs its own network and spends £2 million a day on it, on average. Resellers use that same network for less: the giffgaff plan above gives 20GB for £17 a month less than O2's own 30-day plan.

The pricing also reflects what's bundled in. Every O2 plan includes 5G, Europe Zone roaming up to 25GB and access to O2 Priority, while Plus and Ultimate plans add data rollover and roaming outside Europe. O2 WiFi hotspots aren't part of the deal: O2 says they're free for everyone.

The MVNO trade-off

Tesco Mobile and giffgaff both run on O2's network, so the coverage is O2's. The difference is everything around it: O2 Priority, O2's data rollover and O2's roaming zones don't come with a reseller's plan, which sets its own terms.

Is Tesco SIM the same as O2? For coverage purposes, yes. For everything built around the signal, no.

If you'd buy a weekly Greggs coffee or four cinema tickets a month anyway, Priority claws some value back: O2 puts the savings at up to £3.20 and £37.96 a month. If you never open the app, it adds nothing.

Who benefits from an MVNO instead

If your priority is the lowest possible monthly outgoing, with no interest in rewards or direct carrier support, an MVNO on the O2 network delivers the same coverage at a lower rate. The direct O2 proposition makes most sense for users who value the bundled extras and want a single point of contact when something goes wrong.

How to activate an O2 SIM and keep your number

Activation takes one of two paths. Order a physical SIM online or through the O2 app, and O2 aims to deliver it by Royal Mail within three working days. Go the eSIM route and there's no delivery: you scan a QR code from My O2, and O2 says most activations finish within a few minutes, though some take up to 24 hours. No delivery slot, no small plastic card to lose.

Keeping your number is the part most people overthink.

Text PAC to 65075 while still on your current network. A PAC (porting authorisation code) arrives by return text, usually within minutes. Enter that code when you complete your O2 sign-up, and the switch runs automatically from there.

The number transfers within one working day. Your old SIM deactivates the moment the port completes. You don't need to cancel your previous contract beforehand; submitting the PAC handles that automatically. Contacting your old provider separately is a step many people take out of habit, and it occasionally leads to paying both networks in the same month.

Port on a weekday if you can. Working day means business hours, not 24 hours from the moment you submit.

If you decide to leave O2 when a fixed term ends, switching with a PAC or STAC ends the agreement on the day your new provider activates, and Ofcom says your old provider can't charge notice after the switch date. Leaving without switching means giving 30 days' notice and paying for that period.