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Best SIM only deals 2023: Our pick of the best big-data offers in the UK

Sarah Matthews Max Figgett
16 Mar 2023

The best SIM only deals this month, from all the top mobile network providers

Searching for the best SIM-only deals can be a confusing process because each mobile network promises a range of data limits and extra goodies. But fret not: we've sifted through each of their offers to create a list of the best deals in the UK this January.

As you can see from our at-a-glance list below, deals start from less than £10/mth, but if you're willing to stretch your budget a little, you'll benefit from more data and other perks. Spending more also often results in better value for money, but if you don't use much data, you'll still easily find a good deal that won't break the bank. On average, a £10 SIM-only deal gets you around 10GB of data, which is enough for the majority of users.

With so many mobile service providers to choose from, you're bound to find a deal that suits you in terms of price, data, and speed. Below our at-a-glance list, you'll find our in-depth selection of the best SIM-only deals in ten different categories. After this, you'll find our guide on how to choose the best SIM-only deal for you.

Featured deal: Get DOUBLE data for just £10/mth

This Smarty deal represents insanely good value for money. Right now, you can pick up 60GB of data for just £10/mth on a rolling monthly contract. That's double the usual amount of data £10 will buy you - so don't miss out.
60GB (was 30GB)

Best SIM only deals: At a glance

  • Best budget SIM only deal: Smarty
  • Best SIM only deal for social media: Voxi
  • Best SIM only deal for speed: EE

The best SIM only deals in 2023

1. Smarty: The best budget SIM only deals

Price: From £5/mth | View offers at Smarty

The 4GB for £5/mth deal from Smarty is the cheapest one available at the time of writing and a great offering if you're mainly at home and only use your smartphone sparingly. But the mobile network hasn't finished there: it's also offering a solid 60GB of data for just £10/mth, which is stunning value for money. If you prefer the safety of unlimited data, you can bag an all-you-can-eat plan for just £20/mth.

Key details - Contract length: 30 days; 5G-ready: No; Freebies: Unrestricted UK tethering

View offers at Smarty

2. Voxi: The best SIM only deal for social media and streaming

Price: From £10/mth | View offers at Voxi

Most of us use our mobile data to browse social media websites or access streaming services such as YouTube, Netflix and Amazon Prime Video. Voxi has a brilliant solution because it offers free social media browsing and streaming service usage. Its network is provided by Vodafone to ensure reliable 4G or 5G coverage. As well as the excellent 30GB for £12/mth deal that gets you unlimited video streaming and social media, you can also pick up a whopping 100GB for £20/mth.

Key details - Contract length: 30 days; 5G-ready: Yes; Freebies: Unlimited video streaming and social media

View offers at Voxi

3. Three: The best SIM only deal for unlimited data

Price: £24/mth | View offers at Three

This stunning SIM-only deal from Three gets you all-you-can-use 5G data, minutes and texts for £24/mth. That is a great value SIM that will get you great connectivity, competitive speeds and free 5G access. If you're a true data guzzler, this is the sim to consider.

Key details - Contract length: 24 months; 5G-ready: Yes; Freebies: Personal hotspot and Go Roam Around the World

View offers at Three

4. EE: The best SIM only deal for speed

Price: £28/mth | View offers at EE

EE has consistently been voted the best mobile network in the UK. You can currently grab unlimited data at a capped speed of 100Mbps from this excellent provider for a great price of £28/mth. For uncapped speeds, as well as your choice of EE smart benefit, you can sign up to the higher tier £36/mth plan. Right now, EE is also offering double data on its 125GB plans, which cost £23/mth for capped speeds and £31/mth for uncapped speeds – prices which now get you a massive 250GB data/mth, which you'd be hard pressed to burn through even if you're a big data guzzler. 

These contract also allows you to share data with your family, so if you've got kids who guzzle down data quicker than you do, simply transfer data between each phone for no additional cost. For the higher tier plan, EE's range of smart benefits allow you to choose between a six-month free Apple Music or Apple TV+ subscription, BT Sport, Xbox Game Pass Ultimate and free-roaming abroad, among other options.

Key details - Contract length: 24 months; 5G-ready: Yes; Freebies: Superfast 5G

View offers at EE

5. Vodafone: The best SIM-only deal for 5G speeds

Price: £33/mth | View offers at Vodafone

Vodafone has one of the best offerings when it comes to fast 5G: this unlimited 5G data deal currently costs £33/mth. With this contract, the network promises to give you the fastest available data connection, allowing you to make HD video calls, stream music in high quality and download or update apps on the go without any trouble. If you think 150GB would suit you just fine, you may also opt for Vodafone's most recent deal, which offers this generous data package from just £23/mth.

Key details - Contract length: 24 months; 5G-ready: Yes

View offers at Vodafone

6. Lebara Mobile: The best SIM-only deal for free calling abroad

Price: £20/mth | View offers at Lebara

If you have friends and family living abroad, this deal from Lebara (which runs on Vodafone's network) is a great way to keep in touch with them. Not only is it contract-free, but you get 30GB data and unlimited international minutes free to over 40 countries, covering the US, Australia and a large portion of Europe and Asia.

Key details - Contract length: 30 days; 5G-ready: Yes; Freebies: Unlimited international minutes to 41 countries

View offers at Lebara Mobile

7. Sky Mobile: The best SIM-only deal for Sky customers

Price: From £7/mth | View offers at Sky Mobile

Sky TV is considered to be one of the best UK TV service providers. Its basic packages start at £25/mth, but this gives you access to the entire gamut of channels. The benefit of choosing Sky Mobile is that you can stream Sky content on your mobile without eating into your monthly data allowance and any unused data automatically rolls over to the next month. You can also share your data with up to seven SIMs, so if you're running out of data and your kids have some left (or vice versa), you can move data about to save you buying more. Right now, you can pick up a generous 20GB data for just £10/mth, which is a £5/mth saving. 

Key details - Contract length: 30 days; 5G-ready: Yes; Freebies: Unlimited streaming on Sky apps, unused data is rolled over

View offers at Sky Mobile

8. Giffgaff: The best SIM-only deal for students

Price: £10/mth | View offers at Giffgaff

Students are always looking to save money in whatever way they can, so you'll be delighted to find this bargain monthly Goodybag from Giffgaff. It gets you 20GB of data and unlimited texts and minutes– perfect for when you're out and about in lectures or when you fancy checking in with your family back home. Better still, you'll get £5 bonus credit.

Key details - Contract length: 30 days; 5G-ready: No; Freebies: £5 bonus credit

View offers at Giffgaff

9. iD Mobile: The best SIM-only deal for rollover data

Price: £10/mth | View offers at iD Mobile

The name of the game here is decent data packages at low prices, and with this £10/mth deal for 60GB data, iD Mobile certainly hits the mark. If you want more data, you can pick unlimited for just £18/mth on a 12-month contract. Right now you can also bag the first three months of your contract for half price, which means you only pay £5/mth for 60GB data for the first three months. If that wasn't enough, iD Mobile also offers data rollovers on all contracts, meaning that any spare data you don't use up in a month simply rolls over into the next month at no extra charge.

Key details - Contract length: 24 months; 5G-ready: Yes; Freebies: Data rollover

View offers at iD Mobile

How to choose the best SIM only deal for you

What is a SIM only deal?

A SIM card is the small chip that you insert into your phone to tell it who you are and what mobile phone plan you are on. It stands for subscriber identity module and is used to authenticate the user’s information, including a special number that identifies the phone on the network.

As the name suggests, a SIM only plan covers the cost of the SIM – and, therefore, the cost of being on the network – but not the phone it slots into. That means you’ll need to provide your own handset, whether that’s a case of buying it outright or using a previously owned smartphone.

As you’re only paying for the SIM (and whichever benefits you might get on your specified plan), these contracts tend to be substantially less expensive than their phone counterparts. This makes sense, given that you’re not paying off the price of the handset in addition to the network costs.

Pay monthly or pay as you go?

In this guide, we’ll be covering monthly SIM-only contracts, but it’s worth mentioning the alternative: pay as you go. With these plans, there’s generally no contract and you’re not tied into a given time period with the network provider. Instead, you get a certain amount of minutes, texts and data, and when you run out you can top up your SIM card by choosing to pay a set fee.

We’d recommend a pay-as-you-go plan if you don’t think you’ll be using your phone much, at least not so much that you’ll regularly go through the allotted minutes, texts and data within a month. If you do, you won’t necessarily be saving any money over a monthly plan. Essentially, the benefit of a pay-as-you-go plan is flexibility – not being tied to monthly payments for 12 or 24 months. But that benefit falls away if you end up making monthly payments anyway, probably for a smaller data allowance.

What to look out for when buying a SIM-only deal

Data offerings

There are SIM-only deals with limits on minutes and texts, but these days many plans tend to be unlimited in these regards. Instead, the crux of a contract is its data offering. How much data do you get access to each month? Does the plan have a limit on its data speed?

With the first question, one key thing to consider is how much data you actually need on a monthly basis. An unlimited data plan might bring peace of mind that you won’t run out of internet juice, but it might not be the most cost-effective choice if you actually use less than 30GB.

We have some tips on judging the amount of data you need, but a good starting point is to see how much data you currently use, which can be easily done either via your network provider or your phone. You can do this on an iPhone by going to Settings | Cellular or Settings | Mobile Data. On Android, go to Settings | Network and Internet | Data Usage. See what you currently burn through in a month and use this as a yardstick for judging what your future data needs might be.

In terms of data speeds, this is an easy-to-miss factor that can have a big impact on your overall experience. Vodafone, for example, has a trio of unlimited data plans, but the lowest tier (Unlimited Lite) has a maximum download speed of only 2MB/sec. So while it might not have a cap on overall data usage, this is essentially a cap on the speed you can hope to achieve when using your phone. As a point of reference, Netflix recommends a minimum download speed of 3MB/sec for HD streaming.

Contract length and lifetime cost

Besides data, the next thing you’ll be keeping an eye on is the length of the contract you’re signing up to. Some last 24 months, while others only last 12. If you think you’ve found a good deal, you may want to consider locking it in for a longer period of time. Alternatively, if you like the flexibility of being able to change providers, a shorter plan may be for you. Remember, since you’re not paying off the cost of a handset, your contract will only be paying for the minutes, texts and data plan you’ve picked.

The lifetime cost is the total amount you’d spend over the contract length, and it can be a great way to judge the brutal reality of whether or not you’re saving money. Take a few minutes to plot out the amount you’d spend across the 12 or 24 months for different plans, and compare the results. Some SIM-only contracts might be half price for the first six months, for example. That’s great, except for when the monthly cost skyrockets after that period. Does it even out in the end, or do you actually end up spending more?

Another important thing to consider is the cost of the handset. This will very much depend on your particular situation, but if you’re buying a phone outright you’ll want to factor in that cost when calculating the lifetime total. In a nutshell: is the cost of the handset plus the lifetime cost of the SIM-only contract cheaper or more expensive than the lifetime cost of a monthly phone contract?

Benefits and freebies

Finally, some providers will dangle bonuses to try and tempt you into certain contracts. Sometimes these can be good deals, but often they will be a tactic to convince you into a more expensive contract. That’s not to say you should avoid a tantalising freebie – just look at it through the lens of your lifetime cost.

EE, for example, offers a number of "Smart Benefits" as part of select contracts. These range from access to Apple TV+ or BT Sports Ultimate, to bonus "free" roaming destinations. Are these things you would actually want to buy otherwise? Taking the freebies out of the picture, would you opt for the contract without them? Added extras might sweeten an already good deal, but just remember to look at them critically as part of an overall balance of costs.

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