Deals updated: 1 October 2021
Finding the right Sim-only deal can seem daunting – with a range of data limits to choose from, and some tying you down for as much as 24 months, you’ll need to make sure you choose a package that best serves your needs.
We regularly scour the market to pick what we believe to be great value Sim-only deals across low, medium and high-data packages.
Find out how to get started, browse some great deals, and decide what other considerations you need to take into account.
With most packages now coming with unlimited data and minutes, the main factor driving the price of Sim-only deals is mobile data. In terms of how much data you need, consider how often you use your phone outside your home or place of work (which are both places where you're likely to connect to a wi-fi network).
Also, it's important to note the types of activities you do on your phone. If you only use mobile data for light browsing you needn't pay a lot, but if you like to stream on-demand video on your commute, you'll need a bigger bundle. That's why we've split the best deals into low, medium and high data. We've also included 5G data deals – bear in mind the fast speeds of 5G may mean you use more than you expect.
These deals allow you to access lightning-fast 5G speeds – provided you live in an area with good 5G coverage and own a 5G phone. All deals have unlimited minutes and texts.
If you go through Which? Switch, you can currently get 20GB 5G data for just £10, £8 less than if you go direct to O2.
New O2 customers also get three free months of one popular subscription service of their choice with options including Prime Video, Amazon Music Unlimited and Disney+.
iD Mobile is well known for offering cheap no-frills sim-only deals and this deal is no exception.
Currently, you can get unlimited 5G-ready (which reverts to 4G if not being used on a 5G device) data for just £18 a month on a rolling contract.
You'll also get up to five months of access to Apple Music, Apple Arcade and Apple News+ for free when you sign up.
These deals have an allowance of up to 4GB and will be suitable for people who mainly use their phone through a wi-fi network, or don't use the internet often. This amount of data should be plenty for browsing, light social media use or instant messaging on services such as Facebook, Instagram or WhatsApp. All deals have unlimited minutes and texts.
A new entrant into our mobile network satisfaction surveys, Lebara Mobile has pivoted from being a Sim provider for international calls to a low-cost Sim-only provider.
Lebara is currently offering the first month for half price on most of its packages, meaning you can try it for a month and get 4GB data for just £2.99. Cost is not everything, however, - our reviews will let you know if Lebara Mobile customers think the service is as attractive as the price.
Smarty is currently offering 4GB for £6 a month on a rolling contract, which is a great deal for most mobile phone users.
As an added bonus, if you sign up now, you can get three months at half price, meaning you can get 4GB for just £3 a month.
As a low-cost mobile network, there are not a lot of extra benefits with Smarty although tethering is unrestricted and speed caps do not apply.
These deals have an allowance of between 4GB and 10GB and are suitable for people who often use their phone when out and about, whether that be for social media, music streaming or internet-based voice/video calls. All deals have unlimited minutes and texts.
Smarty makes another appearance for another half-price offer for those going through Which? Switch Mobile.
With this deal, you can get the first three months at half price, meaning you get 8GB of data for just £3.50 a month.
Asda Mobile is a well established mobile network that recently moved from using an EE signal to a Vodafone signal and that has meant that ASDA Mobile is able to offer 5G for the first time so this deal is definitely worth checking out.
Cost is not everything, however - our reviews will let you know if Asda Mobile customers think the service is as attractive as the price.
These deals have an allowance of 10GB and above and are suitable for people who use their phone a lot when out and about, whether to stream high quality video/music on a commute or for creating a for a laptop or other internet devices (if the network provider allows). All deals have unlimited minutes and texts.
Three makes another appearance with a very competitive high-data Sim deal – 30GB of 5G-ready data for just £10 a month.
By using Which? Switch Mobile, you can get this deal for 50% less than if you go to Three directly (where it costs £20 for the same deal.)
As with all Three deals, you also get a personal hotspot allowance.
One of Giffgaff's 'Golden Goodybag' Sim-only deals, this package offers 100GB of 5G-ready data for £20, which is a serious upgrade on the original 80GB of 4G data.
It should be noted that Giffgaff's deals also allow tethering, making this package a viable option if you regularly need to use a hotspot.
Sim-only deals tend to trickle in from providers in the lead-up to Black Friday, just like with many other products. They're traditionally no-fuss affairs, usually increasing the data allowance or reducing the price.
Other incentives, like three months free with a streaming service of your choice on O2, are often available year-round, so don't get sucked in just because something is labelled as a 'Black Friday special'. Similarly, don't be seduced by a high-data allowance if you won't use it.
There are a range of things to consider when shopping for a new Sim-only deal.
You’ll need to decide whether you prefer to be on a rolling monthly plan that offers the flexibility of changing at any time, or tying yourself down to a contract period – typically 12 or 18 months. Usually, longer contracts represent better deals. Providers might offer money off the usual monthly fee as part of a promotion, or a data boost for the same price.
You might also see streaming services added in at no extra cost – in the past, Vodafone has offered a choice of Amazon Prime Video, Spotify, NOW TV and Sky Sports Mobile with its Entertainment bundles. Compare and contrast though – if you won’t use the extra data, or the streaming service, you may still be better off with a rolling monthly Sim, if you can get it at a good price.
There are also a lot of great contract deals, so if you’re in the market for a new phone, it’s worth looking at these as well. If you can afford to purchase a handset outright and get a Sim-only deal, it’s often cheaper in the long run, but this isn’t always the case.
Signal is another consideration. If you know that a particular network is good for your area, you may want to stick with it, but move to a different provider. Or if it isn't, it could be time to move.
Here are the core networks the virtual providers use:
As the new super-fast standard, you'll probably be itching to try out 5G if you have a compatible phone.
If you’ve found a deal that you like, but you’re otherwise happy with your provider, you might be a bit reluctant to switch.
You could try haggling with your mobile provider to see if they can match or better the deal, but if they won’t, switching might be your best option.
Before you switch, it’s worth looking into your new provider to make sure they tick the boxes.
We regularly survey customers of 13 major mobile networks to find out their views on everything from customer service and ease of contacting the provider.