Mobile · Provider guide
O2 SIM-only deals: every plan and the real cost
O2 has 4 deals in our table on 25 Oct 2026, from £20.00 a month. The best value is 100GB Classic Plan at a real cost of £22.50 a month (100GB data · O2 network · 24 months). Its stated price rises are built into every real cost below.
Best-value O2 plan
O2 100GB Classic Plan
100GB data · O2 network · 24 months · £22.50 a month real cost
The lowest real cost here from a national provider on 25 Oct 2026, with fees and stated price rises counted.
Every O2 deal we track
Checked 25 Oct 2026| Provider and package | Data | Contract | Monthly price | Real cost | Deal |
|---|---|---|---|---|---|
O2 100GB Classic Plan Offer price ends 4 November 2026 | Data100GBO2 network · 5G | Contract24 monthsEU roaming included | Monthly price£20.00£22.50 from 1 Apr 2027, then £25.00 | Real cost£22.50 /mo£540.00 over 24 months | See deal at O2 (opens in a new tab) |
O2 Unlimited Classic Plan Offer price ends 4 November 2026 | DataUnlimitedO2 network · 5G | Contract24 monthsEU roaming included | Monthly price£23.00£25.50 from 1 Apr 2027, then £28.00 | Real cost£25.50 /mo£612.00 over 24 months | See deal at O2 (opens in a new tab) |
O2 100GB Ultimate Plan Ultimate plan with 8 benefits | Data100GBO2 network · 5G | Contract24 monthsEU roaming included | Monthly price£26.99£29.49 from 1 Apr 2027, then £31.99 | Real cost£29.49 /mo£707.76 over 24 months | See deal at O2 (opens in a new tab) |
O2 Unlimited Ultimate Plan Ultimate plan with 7 benefits | DataUnlimitedO2 network · 5G | Contract24 monthsEU roaming included | Monthly price£29.99£32.49 from 1 Apr 2027, then £34.99 | Real cost£32.49 /mo£779.76 over 24 months | See deal at O2 (opens in a new tab) |
Ranked by real cost; commission never changes the order. Prices checked on each provider's own site on 25 Oct 2026.
Who O2 suits
O2 suits heavy data users who want 5G, EU roaming and their own network's coverage. Our table has four O2 plans, from 100GB to unlimited data. Bigger plans leave room for streaming, video calls and downloads each month, and EU roaming is included on these plans.
Fair usage applies to these plans, so very heavy use is not unlimited in practice. Check the fair usage rule before you choose.
Every O2 plan in our table runs for 24 months. A 24-month plan is cheaper up front, but it ties you in. If you want to leave with a month's notice, compare 30-day SIMs on our cheapest SIM-only page.
The table shows today's offer prices.
Network and coverage
O2 SIM-only plans run on O2's own 4G and 5G network, so every plan in our table uses the same coverage. The network belongs to Virgin Media O2, a joint venture of Liberty Global and Telefonica, which runs it directly.
Every UK SIM-only brand runs on one of four networks: EE, O2, Vodafone or Three. Brands on the same network share its coverage. So a SIM-only deal on O2 gives you O2 coverage, whichever brand sells it. You can compare price, data and extras without changing your signal.
Want a different network's coverage? Compare EE, Vodafone or Three SIM-only deals.
What it really costs
Every O2 plan in our table runs for 24 months, so compare real cost, not just the monthly price.
Real cost is everything you pay over the contract. It includes each monthly price, every stated price rise and any setup or delivery fee. Take off any reward card cash, then divide the total by the number of months.
Since 17 January 2025, providers must state any price rise in pounds and pence when you sign up. Percentage rises are banned in new contracts.
Read the extras before you choose. Fair usage applies, so check that rule first. O2 also lists Ultimate plans with 7 and 8 benefits, so compare the lists. A 12 or 24-month plan is cheaper up front but ties you in. Sort the table by real cost, then check the date it was last checked.
Straight answers
Questions people ask
- Is O2 good value?
- O2 SIM-only plans can be good value, because every plan includes 5G and EU roaming. Our table lists four O2 plans, from 100GB to unlimited data, ranked by real cost. The 24-month contracts tie you in, so compare the real cost in the table first.
- What network does O2 use?
- O2 SIM-only plans run on O2's own 4G and 5G network. O2 is owned by Virgin Media O2, a joint venture of Liberty Global and Telefonica. Every O2 plan in our table includes 5G, and other brands on the same network share its coverage.
- How do I switch to O2 and keep my number?
- Text PAC to 65075 to get your PAC code, then give that code to O2 when you sign up for a SIM-only plan. Your number moves in one working day. You keep the same number, so friends and family can still reach you without any change.