Whilst getting a new phone on a contract may seem like the easy option, paying for that phone upfront and getting a SIM-only contract makes much better financial sense in the long run if you can afford the initial price of the phone. Our round-up of the best SIM deals in the UK could save you a fortune.

It's worth noting that, even if you choose to opt for a SIM-only deal that requires switching to a new network, you don't need to lose your number. You can keep your number when you use the new text-to-switch service.

Here, we've picked out our favourite SIM-only deals to help you discover the best deals quickly and easily.

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: VOXI, until the end of September you get 8GB data, unlimited social media (includes Facebook, WhatsApp, Snapchat, Twitter, Instagram and Facebook Messenger), unlimited minutes and texts, £10 per month. 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.

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 looking for more advice on how to choose a contract, or want to see some more of the top contracts picked out by our editors for light users, moderate users, heavy users and tablet users, click here. Otherwise, use our comparison tool below for SIM deals tailored to your needs.

If you're studying at the moment, also check out our article on the best phone contracts for students.

Students should also see our dedicated Tech Advisor student deals page.

Compare all SIM deals

Here, you can 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 see which networks offer a contract that'll suit you and your budget. If you're on mobile and can't see the comparison tool below, click here to refresh for an optimised version of the page.

Which SIM-only tariff do you need?

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 you can also get rolling monthly contracts – sometimes at the same price or just a few pounds more expensive – that are ideal for visitors to the UK.

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).

It's worth noting that most operators don't allow you to simply take your SIM out of your smartphone in a tablet. They also often frown upon tethering.

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: 3GB data, unlimited minutes, unlimited texts, 4G - £9 per month. View deal here.

SIM deals for moderate use

Our current favourite moderate use deal is from VOXI, which is powered by Vodafone.

It's an interesting one, because you get 6GB 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: 8GB data, unlimited social media, unlimited calls and texts, 4G - £10 per month. View deal here.

It's also worth checking GiffgaffID and SMARTY for moderate deals that might suit your needs. All are simple, SIM-only providers with attractive options powered by Three or O2. 

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, 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.