A SIM-only deal is what you need when you already have a phone, or if you've bought one outright - and boy do you have a lot of choice. With tons of networks offering plans on a huge range of tariffs, you're bound to find one that suits you and get it at an amazing price.
Of course, all that choice can make things a bit confusing. Here's how to compare SIM-only deals, and narrow them down to find the best one for you.
How to find a SIM-only deal
The best way to find a SIM deal is to compare the lot. Use our comparison tool to see all the deals you can currently get, and alter the filters at the side so it just shows the ones that suit what you need. You can sort them all by cost to see the best value ones too, or even by other things like data allowance.
Need some guidance to pick SIM deal that fits you? Here are a few things to think about.
Monthly allowances on SIM plans are wide-ranging. Some have just 100MB of data and a couple of hundred minutes, while others give you fully unlimited use.
For calls, bear in mind that 1000 minutes per month works out to about half an hour of chatting per day, and work around that. A lot of networks SIMs with unlimited calls, though not always.
The majority of networks offer plans with unlimited texts these days too, but if not, you'll have to do a bit of maths again. 1000 texts per month is about 30 per day - and remember that's SMS texts, not WhatsApp or Facebook Messenger, which are covered by your data allowance instead.
Data is the tricky one. The average smartphone user uses around 2-3GB per month, but it can vary pretty wildly. To work out how much you need, take a look at your current usage, which you may be able to do in your phone's settings or with an app like My Three or My EE.
1GB per month is fine for just browsing, messaging, and email, while 2GB or 3GB lets you browse social media all month without running out of data.
A bigger allowance of 5GB-10GB is enough to get in a few hours of streaming on top of that - though you'll probably need 10GB or more if you stream music or TV every single day, or if you use your phone for work. Three is currently the only network to really offer unlimited data SIMs, which gives you the ideal allowance if you stream or download a lot and want peace of mind.
Take a look at this guide to data allowances for a little more guidance.
You can find SIMs on one-month contracts, 12-month contracts, or even 18-month or 24-month terms.
Generally, longer term plans are cheaper per month - but 30-day ones are more flexible, since you can change or cancel them whenever you like.
Pretty much every network in the UK offers SIM-only deals, so you have loads and loads to choose from.
Some, like giffgaff and iD Mobile, focus on low prices. Others give you bonuses that you can't get from other providers - such as Priority with O2, free app subscriptions with Vodafone, or the country's fastest 4G with EE. A few don't perform credit checks, including Asda Mobile, which is handy if you've been rejected due to bad credit before.
Remember to check providers' coverage before you sign up to make sure you can get signal where you are.
Can I keep my phone number if I switch network?
Yes, you can. You can port your number to and from any mobile network.
All you need to do is sign up to a new SIM, then contact your current network and ask for a PAC number. Hand that over to your new provider, and your phone number will move across to your new SIM in a matter of days.
What size SIM card do I need?
SIM cards come in three sizes: standard, micro, or nano. To check which one you need, take a look at the SIM already in your phone, refer to its user manual, or look it up online.
- Combi-SIM - This kind of SIM is supplied by most networks because it's so convenient. It's a standard-size SIM card that can break down into smaller ones to fit in your phone - whichever one you need, a combi-SIM covers it.
- Standard SIM - A large, full-sized SIM. Not many phones take them any more, but some older ones do - such as the Samsung Galaxy S4.
- Micro SIM - Smaller than a standard SIM. You'll need one of these if you have an iPhone 4s or older, LG G4 or older, Motorola Moto G, or certain Samsungs, HTCs, and Huaweis.
- Nano SIM - The smallest SIM you can get, and the most common choice for recent handsets. That includes the iPhone 5 and newer, Samsung Galaxy S6 or A3 and newer, Sony Xperia Z3 and newer, OnePlus 3 and newer, Motorola X or Z, and the latest HTCs.
What's the cheapest SIM-only deal?
To find cheap SIM deals, use our comparison table and sort everything by cost. This will push the lowest priced plans right to the top so you can see them first.
Lower allowances of course cost less than higher ones overall - but always make sure you have enough for what you use so you don't have to pay extra for bolt-ons later.
Smaller networks with fewer overheads offer cheaper SIMs too. They don't come with as many bonuses or features as larger networks, but prices are noticeably lower. Take a look at networks like Tesco Mobile or iD Mobile.
12-month contracts usually cost less per month than equivalent tariffs on 30-day plans - though 30-day deals are quite competitive these days. It really is best to compare all your options here, if you don't have a preference.
And finally, keep an eye out for existing customer deals. You may be able to find a special upgrade deal from your current network, or even from your broadband or TV provider - such as BT, Sky, or Virgin.