Most people these days get a new phone on contract, but if you can afford to pay for that phone upfront (or you're now out of contract on your phone) it makes much better financial sense to get a SIM-only tariff. In fact, our round-up of the best SIM deals in the UK could save you a fortune in the long run.
A big concern for many is that you'll lose your current phone number if you switch. But that's not true: you can transfer your current phone number to a new network and the whole process is simple if you use the new text-to-switch service.
Here, we've picked the very best SIM-only deals available right now.
For light use: Our favourite SIM deal for light data users is iD's 2GB data, unlimited minutes, unlimited texts, 4G - £7 per month. View deal here.
For moderate use: If you want a bit more data, then Three has a good bundle. 8GB data, unlimited minutes, unlimited texts, 5G - £9 per month on a 12 month contract. View deal here.
Giffgaff also has a good moderate-use option with its £10 goodybag, which gets you 6GB data per month with unlimited texts and minutes. View deal here.
For heavy use: Three, unlimited data, unlimited minutes, unlimited texts, 4G - £10 per month for 6 months, then £20 per month. View deal here.
Don't miss Vodafone's £20 unlimited data SIM-O plan that also includes free access to either Spotify, Now TV, Amazon Prime Video or Sky Sports. See our coverage here.
For heavy use: Giffgaff, 40GB data, unlimited minutes, unlimited tests, 4G - £20 per month, one month rolling. View deal here.
For 5G: Vodafone, unlimited data, minutes and texts, £23 per month. View deal here.
If you're studying at the moment, also check out our article on the best phone contracts for students.
Compare all SIM deals
Use our SIM deals comparison tool to help you find a contract that suits you. Use the sliders and drop down menus to adjust your preferences and filter the list. If you're on mobile and can't see the comparison tool below, click here for an optimised version of the page.
Unlike smartphone contracts, which typically stretch to 24 months, SIM-only deals are much shorter. Most SIM-only deals come with 12-month contracts, but there are many rolling monthly contracts – sometimes at the same price – that are ideal for visitors to the UK or for anyone who doesn't want to be tied in.
The price you pay per month will largely depend on how many minutes and texts you need, and how much data you require.
Plus, you'll need to decide whether your SIM is to go in a tablet (in which case you'll only need data) or a smartphone (in which case you'll want minutes, texts and data).
Most operators don't allow you to simply take your SIM out of your smartphone in a tablet. Some often frown upon tethering, so check the Ts & Cs if you want to use your phone's data connection on your tablet, or a second phone.
Pinning down the best SIM-only contract is tricky due to the huge number of combinations of minutes, texts and data available.
However, most people will fall into one of three camps that we'll focus on here: those who simply want to make the odd call or text, and use their PC to go online; those who make calls and texts, go online, check emails, use apps and perhaps watch the odd video; and those who are permanently glued to their smartphone.
Or, to put that more simply, light, moderate and heavy users.
SIM deals for light use
There are plans available for just £5 per month if you plan on using your SIM for light use.
We'd recommend considering iD, which is Carphone Warehouse's mobile network. All of iD's contracts offer bill capping, data rollover and Roam like at Home making it an even more appealing option with no nasty surprises.
A good option for light users is its 2GB option, which is just £7 per month, but you'll find slightly higher data options that are still priced well there too:
- iD: 2GB data, unlimited minutes, unlimited texts, 4G - £7 per month. View deal here.
- iD: 4GB data, unlimited minutes, unlimited texts, 4G - £9 per month. View deal here.
SIM deals for moderate use
For moderate use, and also for teenagers, the best deal is from VOXI, which is powered by Vodafone.
It's an interesting one, because you get 15GB of data, but social media usage is unlimited and won't eat into that data. That means any Facebook, WhatsApp, Snapchat, Twitter, Instagram, Facebook Messenger, Pinterest and more. Voice and video calls via those apps is not included, but all other activity is.
- VOXI: 15GB data, unlimited social media, unlimited calls and texts, 4G - £15 per month. View deal here.
SIM deals for heavy use
For anyone who wants the freedom to text and use the internet as much as they like, our favourite deal is Three's unlimited data SIM, with unlimited texts and unlimited minutes contract, which is a very reasonable £20 per month. Giffgaff also has a similarly great offer on at the moment.
- Three, unlimited data, unlimited minutes, unlimited texts, 4G - £10 per month for 6 months then £20 per month. View deal here.
- Giffgaff, 40GB data, unlimited minutes, unlimited tests, 4G - £20 per month, one month rolling. View deal here.
Tablet plans (Data SIMs)
You can't simply take the SIM out of your phone and stick it in your tablet. You need to get a SIM that uses a data-only plan (and don't forget that not all tablets offer SIM-card slots, in which case you'll only be able to connect to WiFi).
How much data you need will very much depend on the activities you intend to enjoy on your tablet, plus whether you spend any of your time within range of a Wi-Fi hotspot. If you want a SIM just to cover you on the odd occasion that you use your tablet away from home and need to continue to access your email, you certainly don't need to pay out extra for a 4G plan.
Some of the best SIM-only deals for tablets come from Three, which offers 2GB for £8 per month, 15GB for £18 per month and 40GB for £22 per month. You can view those deals here.