Best SIM-only deals: the UK's top 10 mobile providers compared
Every provider below runs on one of the UK's three networks — so a £6 SIM can get the same coverage as a £25 one. Here's what the ten biggest providers charge right now, and which of them will put your price up next April.
Do these 3 things today
- Text INFO to 85075 (free, from the phone in your hand). Your provider must reply
telling you if you're still in contract and what you'd pay to leave.
Out of contract? You're free to switch today — and if you're paying over £15 a month, you're probably overpaying.
- Pick from the table below — every provider here uses EE, O2, Vodafone or Three's
masts, so check the host network's coverage at your postcode, not the brand name.
75GB for £8 (SMARTY) and 80GB for £10 (iD Mobile) exist right now. Most people use under 10GB a month.
- Text PAC to 65075 to switch and keep your number. Give the code to your new provider —
the switch completes in one working day, and your old contract ends automatically.
No awkward phone call. Your old provider isn't allowed to make you ring them to cancel.
Three deals worth knowing about first
Picks are chosen on price and terms alone. We have no commercial relationship with any provider on this page.
Top 10 providers, ranked by customer numbers
"Cheapest plan" is the provider's lowest-priced standard SIM-only plan; "best value" is the plan that gets you the most for a mid-range budget. The column to watch is the last one — whether your price is locked, or goes up every April.
| Provider | Customers | Cheapest plan | Best value plan | Contract | April price rise? |
|---|---|---|---|---|---|
| 1 · EEEE network | ~25m | £10 · 20GB | £21 · 100GB | 24 mo | +£2.50/mth |
| 2 · O2O2 network | ~24m | £20.50 · 50GB | £22.50 · Unlimited | 24 mo | +£2.50/mth |
| 3 · VodafoneVodafone (VodafoneThree) network | ~17.5m | £16 · 30GB | £26 · Unlimited | 24 mo | +£2.50/mth |
| 4 · ThreeThree (VodafoneThree) network | ~9.9m | £8 · 120GB | £22 · Unlimited | 24 mo | +£1.90/mth (5–99GB); +£2.30/mth for 100GB+ |
| 5 · Tesco MobileO2 network | 5m+ | £9 · 12GB | £15 · 100GB | 24 mo | No annual rise for Clubcard holders (prices frozen); standard (non-Clubcard) prices rise each April |
| 6 · giffgaffO2 network | 4.1m | £6 · 2GB | £14 · Unlimited | Rolling / 18 mo | None — no mid-contract rises |
| 7 · Sky MobileO2 network | 3m+ | £6 · 10GB | £11 · 50GB | 12 mo | In-contract annual rise ~£1.50/mth — applied in February, not April; Sky's April rises are broadband/TV only. New SIM-only sign-ups accept an in-term price-increase notice. |
| 8 · iD MobileThree network | 2.6m | £6 · 8GB | £8 · 50GB | Rolling / 12 mo | None — no annual rises (own site: 'SIM only plans are not subject to annual CPI or RPI price increases') |
| 9 · LebaraVodafone network | 2m+ | £5 · 5GB | £10 · 30GB | Rolling | None — no annual rises |
| 10 · VOXIVodafone network | 1m+ | £10 · 60GB | £15 · 140GB | Rolling | None — price locked |
† EE prices via MoneySavingExpert's live SIM finder (EE's own site doesn't show prices to comparison checks); Lebara prices via SIM Sherpa (June 2026); Sky confirms an annual rise applies but doesn't publish the amount. Everything else checked directly on the provider's website on 31 July 2026. Customer numbers are the latest published or reported figures — see sources below.
The April price rise, in plain English
Since January 2025, providers can't link mid-contract rises to inflation any more — Ofcom makes them state the rise in pounds and pence up front. Sounds better. In practice, the big networks all picked a flat £2.50 a month (EE, O2, Vodafone) or £1.90 (Three), added every April, even though you're mid-contract.
On a £10 SIM, £2.50 is a 25% rise. That's why MoneySavingExpert's June 2026 analysis of 47,000 tariffs found around three-quarters of customers are now paying more under the new rules than they would have under the old inflation-linked ones — and why the government has ordered Ofcom to review the whole regime. Until that lands, the fix is simple: the rolling-plan providers in the table (giffgaff, iD Mobile, Lebara, VOXI, SMARTY) and Tesco's Clubcard prices don't do April rises at all.
Same masts, different price
The UK has three mobile networks: EE, Virgin Media O2, and VodafoneThree (Vodafone and Three merged in 2025 but still sell separately). Every other name in the table rents space on one of them. A £6 SMARTY SIM uses Three's masts; a £5 Lebara SIM uses Vodafone's. You may lose some extras — roaming allowances, phone-upgrade schemes, priority tickets — but not coverage. Check the host network's coverage map for your postcode before you switch, and you know exactly what you're getting.
SIM-only, answered
Will a cheap SIM give me worse signal?
No — coverage comes from the host network's masts, not the brand. A budget SIM on O2's network gets the same O2 coverage as O2's own customers. Speeds can occasionally be deprioritised at very busy times on some budget brands, but for most people it's indistinguishable.
Do I lose my number when I switch?
No. Text PAC to 65075, give the code to your new provider, and your number moves within one working day. If you do not want to keep your number, text STAC to 75075 instead.
What's the catch with rolling (1-month) plans?
Very little — that's why we like them. You can leave or change plan monthly, there's usually no credit check, and none of the rolling providers in our table applies April price rises. The trade-off is fewer perks: no phone bundled, and sometimes less generous roaming.
How much data do I actually need?
Most people use well under 10GB a month — check your last few bills or your phone's settings. If you're mostly on wifi at home and work, 5GB is plenty. Heavy streamers away from wifi should look at the 60GB+ plans, which now start around £8–£10.
Why is there no handset deal here?
This page is SIM-only on purpose. Pay-monthly handset deals bundle a loan for the phone into your bill — they're a credit product, and usually poor value against buying a refurbished phone outright and pairing it with a cheap SIM. We'll cover that properly in a separate guide.
Methodology and sources
Providers are ranked by latest published or reported UK customer numbers. Prices are checked every day, directly on each provider's website wherever possible; where a provider hides prices from automated checks we use a named, dated third-party source and mark the row with a dagger (†). Promotional prices are labelled as promos with their end date where published. We list no affiliate links and earn nothing from any provider on this page.
- Provider price pages: O2, Vodafone, Three, giffgaff, Sky Mobile, iD Mobile, VOXI, Tesco Mobile — checked 31 July 2026
- EE prices: MoneySavingExpert cheap mobile finder; Lebara prices: SIM Sherpa (June 2026)
- Price-rise rules: Ofcom — ban on inflation-linked rises (in force 17 Jan 2025); MSE research on pounds-and-pence rises, June 2026
- Market structure: Vodafone–Three merger completion (May 2025); customer numbers via Which?, ISPreview and provider reports, 2024–2026