Best SIM-Only Deals UK 2025: Cheapest Plans Compared
Find the cheapest SIM-only deals in the UK for 2025. We compare Asda Mobile, VOXI, TalkMobile, Three and EE from just £4.50 per month. Data allowances, 5G access, contract lengths and network coverage compared to find the best value plan.
Introduction: Why Switch to a SIM-Only Deal?
If you are still paying for a phone contract that bundles your handset with your monthly plan, there is a very good chance you are overpaying. Once you own your phone outright, whether you bought it SIM-free or have finished paying off a contract, switching to a SIM-only deal is one of the easiest ways to cut your monthly mobile bill. The savings can be substantial: the average UK consumer pays around £35 to £45 per month on a phone contract, but a SIM-only deal with a generous data allowance can cost as little as £8 to £15 per month. Over a year, that is a saving of £240 to £360.
The SIM-only market in the UK is fiercely competitive in 2025, with dozens of providers fighting for your business. From budget MVNOs (mobile virtual network operators) like Asda Mobile and VOXI to the big four networks (EE, Three, Vodafone and O2), there is a plan to suit every usage pattern and budget. In this guide, we compare the cheapest and best-value SIM-only deals across every data tier, explain the differences between networks, and help you choose the right plan for your needs.
What is a SIM-only deal? A SIM-only deal provides you with a SIM card (or eSIM) that gives you a monthly allowance of data, calls and texts. Unlike a phone contract, it does not include a handset, so the monthly cost is much lower. You insert the SIM into your existing phone and start using it immediately. Most SIM-only deals are available on 1-month rolling contracts (cancel anytime) or 12-month fixed contracts, with 12-month deals typically offering better value.
Best SIM-Only Deals by Data Allowance
Best Deals: 1 - 5 GB Data
If you primarily use your phone for calls, texts, messaging apps and occasional web browsing on Wi-Fi, a small data plan of 1 to 5 GB per month is all you need. These plans are ideal for light users, children's phones, or secondary devices. Here are the best options in 2025.
Asda Mobile 2 GB - £4.50/month
Asda Mobile offers one of the cheapest SIM-only deals in the UK at just £4.50 per month for 2 GB of data, unlimited texts and 100 minutes of calls. The network runs on EE's infrastructure, so coverage and call quality are excellent. The 30-day rolling contract means you can cancel or change your plan at any time without penalties.
For very light users who mainly use Wi-Fi and only need mobile data for occasional browsing and messaging, this is an unbeatable deal. Asda Mobile also offers larger allowances at equally competitive prices if you find you need more data.
TalkMobile 4 GB - £5.50/month
TalkMobile, which uses Vodafone's network, offers 4 GB of data with unlimited calls and texts for just £5.50 per month on a 12-month contract. The Vodafone network provides solid coverage across most of the UK, and TalkMobile includes EU roaming at no extra cost (subject to fair use limits). This is an excellent option for users who want a reliable network without the premium price tag of Vodafone itself.
VOXI 6 GB - £6/month (Under 30s Special)
VOXI stands out from the competition with a unique selling point: social media and messaging apps do not count towards your data allowance. This means WhatsApp, Facebook, Instagram, Snapchat, TikTok, Twitter and many other apps can be used as much as you want without eating into your 6 GB data limit. For heavy social media users, this effectively doubles or triples the usable data allowance.
VOXI runs on Vodafone's network and is available on 30-day rolling contracts. There are no credit checks, and you can manage everything through the VOXI app.
| Provider | Data | Calls | Texts | Contract | Price/Month | Network |
|---|---|---|---|---|---|---|
| Asda Mobile | 2 GB | 100 mins | Unlimited | 30 days | £4.50 | EE |
| TalkMobile | 4 GB | Unlimited | Unlimited | 12 months | £5.50 | Vodafone |
| VOXI | 6 GB | Unlimited | Unlimited | 30 days | £6.00 | Vodafone |
Best Deals: 5 - 15 GB Data
A 5 to 15 GB data plan suits the majority of UK smartphone users. It is enough for regular social media use, music and podcast streaming, email, web browsing and occasional video streaming on mobile data. If you are on Wi-Fi at home and at work, 10 GB of mobile data is more than most people use in a month.
Asda Mobile 10 GB - £7/month
Asda Mobile's 10 GB plan is one of the best-value mid-range SIM-only deals in the UK. For just £7 per month, you get 10 GB of data, unlimited calls and unlimited texts on a 30-day rolling contract. The EE network backbone ensures excellent coverage and fast data speeds. If you need more data one month, you can easily upgrade through the Asda Mobile app without being locked into a longer contract.
TalkMobile 12 GB - £8.50/month
TalkMobile's 12 GB plan offers a generous data allowance with unlimited calls and texts for £8.50 per month on a 12-month contract. Like all TalkMobile plans, it includes EU roaming and runs on the Vodafone network. The 12-month contract provides a lower monthly rate compared to rolling plans, making it ideal if you are happy to commit for a year.
VOXI 15 GB - £10/month
VOXI's 15 GB plan includes unlimited social media and messaging use on top of the 15 GB data allowance, plus unlimited calls and texts. At £10 per month on a 30-day rolling contract, it offers outstanding value for users who are heavy on social media. The combination of 15 GB of general data plus unlimited social media usage means you are unlikely to ever run out of data.
| Provider | Data | Calls | Texts | Contract | Price/Month | Network |
|---|---|---|---|---|---|---|
| Asda Mobile | 10 GB | Unlimited | Unlimited | 30 days | £7.00 | EE |
| TalkMobile | 12 GB | Unlimited | Unlimited | 12 months | £8.50 | Vodafone |
| VOXI | 15 GB + social | Unlimited | Unlimited | 30 days | £10.00 | Vodafone |
Best Deals: 15 - 50 GB Data
If you stream music and videos on the go, use your phone as a mobile hotspot, or simply want the peace of mind that comes with a large data allowance, a 15 to 50 GB plan is the way to go. These plans have become remarkably affordable in 2025, with several providers offering 30 GB or more for under £15 per month.
Asda Mobile 25 GB - £10/month
Asda Mobile's 25 GB plan is exceptional value at just £10 per month. With unlimited calls and texts included, this plan is ideal for moderate to heavy data users who want reliability and value. The EE network ensures fast download speeds and wide coverage. At this price, there is very little reason to settle for a smaller data allowance.
TalkMobile 40 GB - £12.50/month
TalkMobile's 40 GB plan offers a very generous data allowance for under £13 per month. With unlimited calls and texts on Vodafone's network, this is one of the best mid-range deals available. The 12-month contract locks in the price, protecting you against any mid-contract price increases (though TalkMobile is one of the few providers that does not apply annual CPI-linked price rises).
VOXI 45 GB - £15/month
VOXI's 45 GB plan includes unlimited social media, unlimited calls and texts, and a hefty 45 GB data allowance. For users who stream, browse and download heavily, this plan provides ample data with the added benefit of social media not counting towards the allowance. The 30-day rolling contract means you can upgrade to unlimited data or downgrade at any time.
| Provider | Data | Calls | Texts | Contract | Price/Month | Network |
|---|---|---|---|---|---|---|
| Asda Mobile | 25 GB | Unlimited | Unlimited | 30 days | £10.00 | EE |
| TalkMobile | 40 GB | Unlimited | Unlimited | 12 months | £12.50 | Vodafone |
| VOXI | 45 GB + social | Unlimited | Unlimited | 30 days | £15.00 | Vodafone |
Best Unlimited Data Deals
If you never want to think about data limits, an unlimited plan is the ultimate peace of mind. Unlimited data has become increasingly affordable in 2025, with several providers now offering it for under £20 per month. These plans are ideal for people who stream video extensively, use their phone as a hotspot for their laptop, or live in areas with poor broadband where mobile data is their primary internet connection.
VOXI Unlimited - £20/month
VOXI's unlimited data plan is one of the cheapest in the UK, offering unlimited data, calls and texts for just £20 per month on a 30-day rolling contract. The social media and messaging benefits are included as standard, though they are somewhat redundant when you have unlimited data. The Vodafone network provides reliable 4G and 5G coverage across most of the UK.
TalkMobile Unlimited - £18/month
TalkMobile offers unlimited data on Vodafone's network for just £18 per month on a 12-month contract, making it one of the cheapest unlimited plans available. With unlimited calls and texts included, plus EU roaming, this is a superb deal for heavy data users who are happy to commit for a year. TalkMobile does not apply mid-contract price rises on its 12-month plans, which is a significant advantage over many larger providers.
View TalkMobile Unlimited Deal
Three Unlimited - £22/month
Three has long been known for its generous data allowances, and its unlimited plan at £22 per month on a 24-month contract includes unlimited 5G data. Three's 5G network is expanding rapidly and offers some of the fastest mobile data speeds in the UK. If you are in an area with Three 5G coverage, this is an excellent choice for those who want the fastest possible mobile internet speeds.
EE Unlimited - £28/month
EE is the UK's largest and fastest mobile network, and its unlimited plan reflects this with a higher price tag of £28 per month on a 24-month contract. What you get in return is the best coverage and fastest speeds of any UK network, with 5G available in more locations than any competitor. EE also includes additional perks like Apple Music or Xbox Game Pass on some plans, and its customer service is consistently rated among the best in the industry.
| Provider | Data | 5G Included | Contract | Price/Month | Network |
|---|---|---|---|---|---|
| TalkMobile | Unlimited | No (4G only) | 12 months | £18.00 | Vodafone |
| VOXI | Unlimited | Yes | 30 days | £20.00 | Vodafone |
| Three | Unlimited | Yes | 24 months | £22.00 | Three |
| EE | Unlimited | Yes | 24 months | £28.00 | EE |
Understanding UK Mobile Networks
The UK has four physical mobile networks: EE, Three, Vodafone and O2 (now part of Virgin Media O2). All other mobile providers, known as MVNOs (Mobile Virtual Network Operators), piggyback on one of these four networks. Understanding which network a provider uses is important because it determines your coverage, data speeds and call quality.
Network Coverage Comparison
Which network has the best coverage? EE has the widest 4G coverage in the UK, reaching approximately 99% of the population. Vodafone and O2 are close behind at around 98%. Three has the smallest 4G footprint at around 97%, but its 5G rollout is among the most aggressive. For rural areas, EE is generally the safest choice. You can check coverage in your specific area using each network's online coverage checker before committing to a plan.
| Network | 4G Coverage | 5G Coverage | Used By | Strengths |
|---|---|---|---|---|
| EE | 99% | Most extensive | Asda Mobile, BT Mobile | Fastest speeds, widest coverage |
| Vodafone | 98% | Growing | VOXI, TalkMobile, Lebara | Good international roaming |
| Three | 97% | Expanding quickly | Smarty, iD Mobile | Generous data, competitive 5G |
| O2 / VMO2 | 98% | Growing | Giffgaff, Tesco Mobile | O2 Priority rewards |
Which Providers Use Which Network?
Here is a quick reference for the main budget and mid-range providers and the network they use.
- EE network: Asda Mobile, BT Mobile, Plusnet Mobile
- Vodafone network: VOXI, TalkMobile, Lebara
- Three network: Smarty, iD Mobile
- O2 network: Giffgaff, Tesco Mobile, Sky Mobile
In general, MVNOs offer the same coverage as their parent network but at lower prices. The trade-off is that MVNOs may have slightly lower data speed priorities during peak times, and customer support may be more limited. However, for most users, the difference is imperceptible.
5G: Is It Worth Paying Extra?
5G is the latest generation of mobile network technology, offering significantly faster data speeds and lower latency than 4G. In ideal conditions, 5G can deliver download speeds of 300 Mbps or more, compared to 30 to 50 Mbps on 4G. However, there are several factors to consider before paying extra for a 5G plan.
5G Coverage in the UK
As of 2025, 5G coverage in the UK is still predominantly concentrated in major cities and towns. EE has the most extensive 5G network, covering over 50% of the UK population, followed by Three and Vodafone. If you live and work in a major urban area, you are likely to have good 5G coverage. If you are in a rural or suburban area, you may rarely connect to 5G, making it less worthwhile to pay a premium for it.
Do You Need a 5G Phone?
To use 5G, you need a 5G-compatible phone. All of the smartphones in our best phones under £500 guide support 5G. If your phone is more than three or four years old, it may only support 4G, in which case a 5G plan would offer no benefit.
Our advice: If 5G is included in a plan at the same price as 4G only, always choose the 5G option as it future-proofs your plan. However, do not pay more than £2 to £3 extra per month for 5G unless you live in an area with confirmed 5G coverage and regularly need fast mobile data speeds. For most people, 4G is more than fast enough for everyday tasks.
Contract vs Pay As You Go (PAYG)
SIM-only deals come in three main contract types, each with its own advantages.
30-Day Rolling Contracts
A 30-day rolling contract gives you maximum flexibility. You can cancel, upgrade or downgrade your plan at any time with just 30 days' notice. This is ideal if you are unsure how much data you need, if you are between providers, or if you simply do not want to be tied into a long commitment. Providers like VOXI and Asda Mobile specialise in rolling contracts.
Pros of 30-Day Contracts
- Cancel or change plan at any time
- No credit check required with some providers
- Try a network before committing long-term
- No exit fees or penalties
Cons of 30-Day Contracts
- Monthly price is typically higher than 12-month deals
- Provider can change terms with 30 days' notice
- May miss out on promotional pricing tied to longer contracts
12-Month Contracts
A 12-month contract locks you in for a year but typically offers a lower monthly price than a rolling deal. This is the sweet spot for most users: you get a good discount without being tied in for too long. TalkMobile and most major networks offer competitive 12-month SIM-only deals.
24-Month Contracts
Some providers, particularly the major networks like EE, Three and O2, offer 24-month SIM-only contracts. These can offer the lowest monthly prices, but you are locked in for two years. Be aware that many 24-month contracts include annual CPI-linked price increases, which means your bill could go up by 5 to 10% each year. Always check the terms carefully before signing up.
Pay As You Go (PAYG)
PAYG is the most basic option: you top up credit and pay for calls, texts and data as you use them. PAYG has become less popular as SIM-only deals have dropped in price, but it remains useful for people who use their phone very rarely, as a spare or emergency phone, or for travellers who want a temporary UK number. Some PAYG plans now offer bundles (for example, £10 top-up gives you a set amount of data and minutes for 30 days), which blur the line with SIM-only deals.
How to Switch Your SIM-Only Provider
Switching your SIM-only provider has become much easier in recent years thanks to the PAC code system and, more recently, the One Touch Switch process introduced in 2024.
One Touch Switch Process
- Choose your new plan: Select the SIM-only deal you want from your new provider and order it online.
- Request a switch: When you sign up with your new provider, tell them you want to keep your existing phone number. They will contact your current provider on your behalf through the One Touch Switch system.
- Receive your new SIM: Your new SIM will arrive within one to two business days (or instantly if you choose an eSIM).
- Automatic transfer: Your number will transfer to your new SIM automatically on the agreed date. There is typically less than one hour of downtime during the switch.
- Old contract cancelled: Your old provider will automatically cancel your contract once the switch is complete. You do not need to contact them separately.
Switching tip: If you are on a 12-month or 24-month contract and want to switch before it ends, check whether you need to pay an early termination fee. Most providers charge the remaining monthly payments multiplied by a reduced rate. However, if you are outside your minimum term (i.e., on a rolling basis after your contract ended), you can switch at any time without penalties.
How to Choose the Right Data Allowance
Choosing the right data allowance is important to avoid paying for data you do not use or, worse, running out mid-month and facing reduced speeds or extra charges. Here is a guide to how much data common activities use.
| Activity | Data Usage Per Hour | Monthly Usage (1 hr/day) |
|---|---|---|
| Web browsing | 60 MB | 1.8 GB |
| Social media (scrolling) | 150 MB | 4.5 GB |
| Music streaming (Spotify) | 70 MB | 2.1 GB |
| Video streaming (SD) | 700 MB | 21 GB |
| Video streaming (HD) | 1.5 GB | 45 GB |
| Video calls (Zoom) | 800 MB | 24 GB |
| Email and messaging | 20 MB | 0.6 GB |
| Sat nav (Google Maps) | 10 MB | 0.3 GB |
Check your current usage: The easiest way to choose the right data allowance is to check how much data you currently use each month. On iPhone, go to Settings > Mobile Data. On Android, go to Settings > Network > Data Usage. Your current provider's app will also show your monthly usage history. Most people use between 4 and 8 GB per month, but heavy streamers can easily use 20 GB or more.
Watch Out For: Hidden Costs and Price Rises
Before signing up for any SIM-only deal, be aware of potential hidden costs and gotchas that could increase your bill.
Mid-Contract Price Rises
Many UK mobile providers, including EE, Three, Vodafone and O2, include a clause in their contracts that allows them to increase your monthly price in line with CPI (Consumer Price Index) inflation, typically with an additional percentage on top. For example, a provider might raise prices by CPI + 3.9% each April. On a £20 per month plan, this could add £1 to £2 per month, which adds up over a 24-month contract.
Budget providers like Asda Mobile, VOXI and TalkMobile generally do not apply mid-contract price rises, which is another reason they offer better value overall.
Out-of-Allowance Charges
If you exceed your data allowance, different providers handle it differently. Some throttle your speed to a very slow rate (typically 256 Kbps) until your next billing date, while others charge for additional data. Check your provider's out-of-allowance policy before signing up. Most budget providers simply throttle speeds rather than charging extra, which prevents unexpected bills.
International Roaming
Since Brexit, free EU roaming is no longer guaranteed. Some providers still include it (TalkMobile, for example), while others charge daily fees of £2 to £6 for using your phone in Europe. If you travel frequently, check the roaming policy carefully. VOXI charges a daily roaming fee in Europe, while Asda Mobile offers roaming bundles that can be added when you travel.
Full Comparison Table: Best SIM-Only Deals UK 2025
| Provider | Data | Calls & Texts | Contract | 5G | Price/Month | Network |
|---|---|---|---|---|---|---|
| Asda Mobile | 2 GB | 100 mins, unlimited texts | 30 days | No | £4.50 | EE |
| TalkMobile | 4 GB | Unlimited | 12 months | No | £5.50 | Vodafone |
| VOXI | 6 GB + social | Unlimited | 30 days | No | £6.00 | Vodafone |
| Asda Mobile | 10 GB | Unlimited | 30 days | No | £7.00 | EE |
| TalkMobile | 12 GB | Unlimited | 12 months | No | £8.50 | Vodafone |
| VOXI | 15 GB + social | Unlimited | 30 days | No | £10.00 | Vodafone |
| Asda Mobile | 25 GB | Unlimited | 30 days | No | £10.00 | EE |
| TalkMobile | 40 GB | Unlimited | 12 months | No | £12.50 | Vodafone |
| VOXI | 45 GB + social | Unlimited | 30 days | No | £15.00 | Vodafone |
| TalkMobile | Unlimited | Unlimited | 12 months | No | £18.00 | Vodafone |
| VOXI | Unlimited | Unlimited | 30 days | Yes | £20.00 | Vodafone |
| Three | Unlimited | Unlimited | 24 months | Yes | £22.00 | Three |
| EE | Unlimited | Unlimited | 24 months | Yes | £28.00 | EE |
Frequently Asked Questions
Can I keep my phone number when I switch?
Yes. When you sign up with a new provider, simply tell them you want to keep your existing number. The One Touch Switch process will transfer your number automatically within one to two business days. There is typically less than one hour of downtime during the transfer.
Do I need a new SIM card or can I use an eSIM?
Most modern smartphones (iPhone XS and later, Samsung Galaxy S20 and later, Google Pixel 3a and later) support eSIM, which allows you to activate your new plan digitally without waiting for a physical SIM card to arrive. Many providers now offer eSIM activation, including VOXI, EE and Three. Asda Mobile and TalkMobile currently still use physical SIM cards.
What happens if I run out of data?
Most budget providers (Asda Mobile, VOXI, TalkMobile) simply slow your data speed rather than charging extra. The reduced speed (typically 256 Kbps) is enough for basic messaging and email but not for streaming or heavy browsing. You can usually purchase a data add-on through the provider's app if you need more data before your next billing date.
Are SIM-only deals cheaper than phone contracts?
Almost always, yes. A phone contract bundles the cost of a handset with your monthly plan, and you end up paying a premium for the convenience. Buying a phone outright (or on interest-free credit) and pairing it with a SIM-only deal is typically £100 to £300 cheaper over 24 months, depending on the phone and data plan you choose.
Can I use a SIM-only deal in a tablet or mobile router?
Yes. Most SIM-only deals can be used in any SIM-compatible device, including tablets, mobile Wi-Fi routers and laptops with SIM slots. However, be aware that some providers restrict tethering or hotspot usage on certain plans, so check the terms before signing up if you plan to use the SIM in a device other than a phone.
Which is the cheapest SIM-only deal in the UK?
As of 2025, the cheapest SIM-only deal with a data allowance is Asda Mobile at £4.50 per month for 2 GB of data, unlimited texts and 100 minutes. For unlimited calls and texts, TalkMobile's 4 GB plan at £5.50 per month is the cheapest option.
Final Verdict
The UK SIM-only market is incredibly competitive in 2025, and the biggest winners are consumers. For most people, we recommend starting with a plan in the 10 to 15 GB range, which costs between £7 and £10 per month and provides plenty of data for typical use. If you find you consistently use less than half your allowance, downgrade to save money. If you regularly exceed it, upgrading to a larger plan is easy with most providers.
Our top overall pick is Asda Mobile for its unbeatable prices, flexible 30-day contracts and excellent EE network coverage. For social media enthusiasts, VOXI is the standout choice thanks to its unlimited social media data feature. And for users who want the best value on a 12-month contract with unlimited data, TalkMobile at £18 per month is hard to beat.
Whatever your data needs and budget, switching to a SIM-only deal is one of the simplest ways to reduce your monthly outgoings without any compromise in quality. Use PriceDetective to compare the latest deals and find the perfect plan for your usage.