Cheapest SIM Only Deals UK – Compare Plans and Start Saving
Finding the cheapest SIM only deals in the UK can feel like navigating a maze of introductory offers, variable speeds, and network perks. With prices changing frequently and new plans appearing every month, knowing where to look and what to prioritise makes all the difference.
Mobile virtual network operators (MVNOs) such as Lebara, Smarty, and iD Mobile have reshaped the market by offering plans that run on the same infrastructure as the major networks but at a fraction of the price. At the same time, EE, O2, and Vodafone continue to push premium packages with added benefits. The result is a wide spectrum of options that suit different budgets and usage habits.
What are the cheapest and best SIM only deals in the UK?
Key insights from current market data:
- Lebara (Vodafone network) consistently offers the cheapest low-data plans, e.g., 3GB at £1.38/month for first 6 months.
- Martin Lewis recommends checking cashback sites (TopCashback, Quidco) for additional savings on SIM-only deals.
- Unlimited data deals from Vodafone cost around £27.50/month, but smaller MVNOs can be cheaper.
- Comparing total cost over 12 months (including any introductory discounts) reveals true cheapest deal.
- EE and O2 often have higher prices but include perks like BT Sport or cinema tickets.
| Fact | Detail | Source |
|---|---|---|
| Cheapest 3GB deal | Lebara at £1.38/month (first 6 months, then £4.40/month) | moneysavingexpert.com |
| Cheapest 5GB deal | Lebara at £5/month | Lebara |
| Cheapest unlimited data | Smarty at £18/month | Reboxed |
| iD Mobile unlimited | £8/month for 3 months, then £16/month | MSE |
| O2 40GB deal | £8/month until April 2027 | Uswitch |
| EE unlimited plan | £35/month | Reboxed |
| Three Unlimited Max | £45/month | Reboxed |
| Lebara 15GB | £1.31/month for first 9 months, then £7.90/month | MSE |
| EE 2GB No Frills | £19/month | Reboxed |
| EE 25GB Essentials | £28/month | Reboxed |
Which SIM only deals offer unlimited data?
Unlimited data plans have become significantly more affordable in recent years, driven largely by MVNOs competing aggressively on price. The best value propositions no longer come from the traditional major networks but from smaller operators that use their infrastructure.
Smarty – the cheapest consistent unlimited option
Smarty offers unlimited 5G data, along with unlimited UK minutes and texts, for £18/month. This makes it the most affordable unlimited plan from the available data, undercutting major networks by a wide margin. Smarty runs on the Three network and provides rolling monthly contracts without long-term commitments.
iD Mobile – strong introductory value
iD Mobile’s unlimited SIM is priced at £8/month for the first three months, rising to £16/month thereafter. The plan also includes a voucher that improves the effective overall value. iD Mobile uses the Three network and is frequently highlighted by MoneySavingExpert as a top pick for cost-conscious users who want unlimited data.
Major network unlimited plans
For those who prefer a big-brand provider, Vodafone offers unlimited data at £27.50/month on a 12-month contract, while EE charges £35/month for its unlimited plan. Three’s Unlimited Max plan is priced at £45/month. These options include faster speeds and often bundle entertainment perks, but cost significantly more than the MVNO alternatives.
Many unlimited data plans apply a fair usage policy or speed throttle after a certain threshold. Exact limits change per provider and are not always clearly advertised. Users who stream heavily or tether should check the specific terms before committing.
According to Which? – Best SIM-Only Deals, comparing total cost over 12 months is the only reliable way to judge value, especially when introductory discounts end.
What are the top 5 SIM only deals in the UK?
Based on price, value, and frequency of expert recommendation, the following five deals stand out in the current market. Each suits a different type of user.
1. Lebara – 5GB for £5/month
Lebara’s £5 plan includes 5GB of 5G data, 1,000 UK minutes, and 1,000 UK texts. It runs on the Vodafone network, offering strong coverage at a low price. This is the strongest option for anyone seeking a low monthly bill with moderate data needs.
2. Smarty – Unlimited 5G for £18/month
Smarty provides unlimited data with no fixed contract at £18/month. It is the cheapest unlimited plan available from the research and a clear winner for heavy data users on a budget.
3. iD Mobile – Unlimited for £8/month then £16/month
iD Mobile’s unlimited plan starts at a very low introductory rate and settles at a competitive ongoing price. The inclusion of a voucher adds further value, making it a top pick for those who want unlimited data without paying a premium.
4. O2 – 40GB 5G for £8/month initially
O2’s 40GB deal is priced at £8/month until April 2027, after which prices rise annually by £2.50. The plan includes 25GB roaming in 48 destinations and O2 Priority ticket access. It is a strong choice for mid-range users who value perks and travel.
5. EE – 25GB or unlimited from £28/month
EE is the most expensive option among the top five, with 25GB at £28/month and unlimited at £35/month. It is better suited to users who prioritise a premium network experience over cost.
Introductory discounts can make a plan look far cheaper than it actually is. The true measure of value is the total amount paid over a full year. A plan with a low first three months but a high standard rate may end up costing more than a consistently priced alternative.
What are the best SIM only deals according to Martin Lewis?
MoneySavingExpert, founded by Martin Lewis, is one of the most trusted sources for SIM-only comparisons in the UK. Its methodology focuses on the lowest effective monthly cost, especially for rolling or short contracts.
Top MSE picks for low data users
For users who need very little data, MSE highlights Lebara’s 3GB plan at £1.38/month for the first six months (then £4.40/month). The 5GB Lebara plan at £1.50/month for the first seven months (then £4.90/month) and the 15GB option at £1.31/month for the first nine months (then £7.90/month) also feature prominently.
MSE’s unlimited recommendation
For unlimited data, MSE points to iD Mobile as the top pick. The plan’s combination of a low introductory rate and a reasonable ongoing price gives it the best effective annual cost among unlimited options.
Why MSE favours Lebara and iD Mobile
Both providers use major network infrastructure (Vodafone for Lebara, Three for iD Mobile) while charging substantially less. MSE also advises checking cashback sites such as TopCashback and Quidco, which can reduce the effective cost further.
Nearly all SIM-only deals with low headline prices revert to a higher standard rate after the promotional period. Mark the renewal date and consider switching before the price increase applies. Most providers allow a 30-day rolling contract switch without penalty.
What are the best SIM only deals from EE, Lebara, and O2?
EE SIM only deals
EE positions itself as a premium network. Its cheapest plan, the No Frills 2GB option, costs £19/month. The Essentials plan with 25GB is £28/month, and the unlimited plan is £35/month. EE is not competitive on price but offers strong speed and customer service for those willing to pay more. See their current offers at EE SIM-Only Deals.
Lebara SIM only deals
Lebara is the value leader across every data tier. Its 5GB plan at £5/month is the cheapest mainstream option available. Higher-tier plans such as 15GB at £1.31/month for the first nine months also provide excellent value. Lebara uses the Vodafone network, so coverage matches Vodafone’s at a lower price. Full details at Lebara SIM-Only Deals.
O2 SIM only deals
O2 is not the cheapest network, but it offers tangible extras. A standout deal is 40GB 5G data for £8/month until April 2027, with inclusive 25GB roaming in 48 destinations and O2 Priority ticket access. O2 also bundles entertainment perks such as Apple Music, Disney+, Amazon Prime, or Audible depending on the plan. Check O2 SIM-Only Deals.
How have SIM only deal prices changed recently?
SIM-only pricing has seen several notable movements in the past year. The table below summarises the key changes from available data.
- May 2025 – Uswitch updated its comparison page with deals for 2026, indicating forward-looking pricing and continued competition among providers.
- Ongoing – Vodafone increased its unlimited data plan price to £27.50/month, up from £25/month previously.
- Ongoing – Lebara continues to offer its 3GB plan at £1.38/month for the first six months, maintaining its position as the cheapest low-data option.
The broader trend shows MVNOs gaining market share by undercutting major networks, while inflation-linked price rises (such as RPI+3.9% on some contracts) are pushing up standard rates across the board.
What do we know and what remains uncertain about SIM only deals?
| Established information | Information that remains unclear |
|---|---|
| SIM-only deals are generally cheaper than handset contracts. | Prices vary week to week; introductory offers expire without warning. |
| Major networks (EE, Vodafone, O2, Three) have set prices that change rarely. | Unlimited data plans often have speed restrictions after a fair usage threshold – exact limits change per provider. |
| MVNOs like Lebara, iD Mobile, and Smarty offer lower prices but use parent network coverage. | Contract prices can increase annually (e.g., RPI+3.9% for some networks). |
| – | Coverage quality differs by location; always check network coverage maps before switching. |
What makes SIM only deals the most cost-effective option?
SIM-only plans are the most cost-effective way to get mobile service if you already own a handset. The cheapest deals come from MVNOs that piggyback on major networks, often offering identical coverage at a fraction of the price. Consumers must weigh data needs, contract flexibility, and network reliability when choosing. Expert recommendations like Martin Lewis’s MoneySavingExpert provide a trusted starting point but should be cross-checked with current offers.
For a broader look at mobile phone savings, see Best mobile phone deals UK. If you are planning a switch, the guide on How to switch mobile network walks through the process step by step.
Where can you find trusted SIM only deal recommendations?
Several independent sources regularly update their comparisons with current pricing and expert analysis. Below are two of the most frequently cited authorities.
“If you don’t need much data, our top pick is this 3GB/month Lebara Sim (uses Vodafone’s network). It’s £1.38/month for the first six months.”
– MoneySavingExpert (Martin Lewis) at moneysavingexpert.com
“Compare our cheapest 2026 SIM only deals and save money with all the major UK networks.”
– Uswitch at uswitch.com
Other reliable sources include Vodafone SIM-Only Plans, Which? – Best SIM-Only Deals, and network-specific pages such as EE SIM-Only Deals, O2 SIM-Only Deals, and Lebara SIM-Only Deals.
Which SIM only deal is right for you?
If your priority is the lowest possible monthly bill, Lebara’s £5 5GB plan is the strongest option. For unlimited data at a reasonable price, Smarty at £18/month or iD Mobile’s unlimited plan offer the best value. O2 suits users who want perks and roaming, while EE remains a premium choice for those willing to pay more for a major-network experience. Cross-referencing expert picks with current pricing and checking total annual cost will help you avoid surprises when introductory discounts expire.
Frequently asked questions
Can I keep my existing phone number on a SIM-only deal?
Yes, you can usually port your number to the new network via a PAC code from your current provider.
Are SIM-only deals credit checked?
Some contract SIM-only deals require a soft credit check; pay-as-you-go SIMs do not.
What happens after the initial promotional period?
The price typically increases to the standard rate. You can switch or renegotiate before the hike.
Do unlimited data plans have any hidden limits?
Many unlimited plans apply a fair usage policy or throttle speeds after a certain data threshold. Check the provider’s terms for exact limits.
Is 5G included in all SIM-only deals?
Most current deals include 5G at no extra cost, but some budget plans may be limited to 4G. Always confirm before ordering.
Can I use a UK SIM-only deal when travelling abroad?
Roaming policies vary. O2 includes 25GB roaming in 48 destinations, while other providers may charge extra or restrict usage.
How quickly can I switch to a new SIM-only provider?
With a 30-day rolling contract, you can switch within a month. Many providers also offer instant eSIM activation.
Are there any setup fees on SIM-only deals?
Most SIM-only deals have no setup or activation fees, but a few may charge a small delivery cost for the physical SIM.
What network does Lebara use?
Lebara operates on the Vodafone network, so coverage is identical to Vodafone’s at a lower price.
Do I need a new phone number when switching to a SIM-only deal?
No. You can request a PAC code from your current provider and keep your existing number when you move to the new SIM.
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