O2 is one of the UK's largest mobile networks, and its SIM only packages cover everything from flexible 30-day rolling plans to longer 24-month contracts at a lower monthly price. Every O2 SIM only deal comes with the same core perks — O2 Priority, inclusive roaming and O2 Wi-Fi — so the main choice is really about contract length and data allowance.
1. O2 SIM only contract lengths
O2 sells SIM only packages across three main contract lengths, and the right one depends on how much flexibility you want versus how low a monthly price you're chasing.
- 30-day SIM only deals roll month to month with no long-term commitment, so you can leave or switch plans whenever you like — useful if you're not sure how much data you need yet, or you want to stay flexible.
- 12-month SIM only deals trade some of that flexibility for a lower monthly price, without tying you in for a full two years.
- 24-month SIM only deals usually carry O2's lowest monthly price for a given data allowance, in exchange for the longest commitment.
If 5G matters to you specifically, O2's 5G SIM only deals filter down to plans with 5G access built in, though most current O2 packages include it as standard where coverage allows.
2. What's included with every O2 SIM only package
Every O2 SIM only plan comes with the same set of extras regardless of contract length or data allowance:
- O2 Priority — early access to gig and event tickets, plus regular discounts and freebies from partner brands.
- Inclusive roaming — use your UK allowance in a range of EU and worldwide destinations at no extra cost, subject to fair use limits.
- O2 Wi-Fi — automatic access to O2's Wi-Fi hotspots around the UK.
- O2 Volt — if you also have Virgin Media broadband at home, O2 Volt can double your mobile data allowance and add other perks at no extra cost.
These benefits don't change the headline price, but they're worth factoring in if you're comparing O2 against a network or MVNO that doesn't offer the same extras.
3. O2's network coverage
O2 is one of the UK's four national mobile network operators, so coverage is generally strong in towns and cities, with reasonable rural reach that varies by area. If you're switching from another network, check O2's coverage checker for your postcode before committing, particularly if you live or work somewhere with patchy signal already.
4. How to find the cheapest O2 SIM only deal
The lowest monthly price for a given data allowance usually comes from a 24-month contract, but that's only good value if you're confident you'll want to stay on O2 for the full term. If you'd rather see the lowest price across every contract length side by side, our cheapest O2 SIM only deals guide ranks them for you.
A few things to check before you commit to any O2 SIM only package:
- Match the data allowance to what you actually use — an unlimited plan costs more than you need if you rarely stream or download over mobile data.
- Compare the total cost over the full term, not just the monthly headline price, especially when weighing a 24-month deal against rolling shorter contracts.
- Check for new-customer pricing — O2's best rates are often reserved for new SIM only customers rather than existing ones upgrading.
5. O2 vs other networks
O2 sits alongside EE, Vodafone and Three as one of the UK's main networks, with a range of MVNOs — including giffgaff and Sky Mobile — running on the O2 infrastructure at a lower price. If you want O2's coverage without paying O2's own prices, it's worth comparing giffgaff SIM only deals and Sky Mobile SIM only deals alongside O2's own packages. For a wider view across every UK network, see our full SIM only comparison.
6. Frequently asked questions
What SIM only packages does O2 offer?
O2's SIM only packages run from rolling 30-day plans to 12 and 24-month contracts, with data allowances from a few gigabytes up to unlimited. Every package includes O2 Priority, inclusive roaming and O2 Wi-Fi.
Which O2 SIM only deal is cheapest?
The cheapest monthly price for a given data allowance is usually on a 24-month contract, but check our cheapest O2 SIM only deals guide for the current best-value packages across every term.
Can I use my O2 SIM only data abroad?
Most O2 SIM only plans include inclusive roaming in a range of EU and worldwide destinations at no extra cost, subject to fair use limits — check the specific plan for exactly which countries are covered.
Does O2 offer 5G on its SIM only plans?
Most current O2 SIM only packages include 5G access as standard where coverage allows. See our O2 5G SIM only deals guide if you want to filter specifically for it.
7. Conclusion
O2's SIM only packages cover every contract length from flexible 30-day rolling plans to lower-cost 24-month terms, all backed by the same O2 Priority, roaming and Wi-Fi perks. Compare the options above by contract length and data allowance, or head to our cheapest O2 SIM only deals guide if price is your main priority.
