With mobile internet getting faster and faster, SIM-only deals no longer stop with smartphones. Some tablets, including Apple iPads and the Samsung Galaxy Tab A, S5 and S6, ship in 4G or LTE variants that can keep you connected wherever you go using a built-in 4G modem, and the same is true of some high-end laptops. What’s more, you can now buy 4G routers and portable wireless hotspots that can be used to connect your laptops, smartphones and tablets to a mobile network, either in the home or while you’re travelling around.

Regular SIM-only and PAYG deals don’t make much sense here, as you’re paying for call minutes, texts and other services that you don’t need and can’t use. Data-only SIMs are a smarter choice, as you’re only paying for a specific amount of data and not the calls or texts on top. Some will even work in a spare or secondary smartphone that you don’t want to use to make or take calls. For instance, you might have a big-screen device for watching video or gaming, but a smaller phone for everyday use and calls. A data-only SIM saves you paying for two more expensive SIM plans.

Think carefully, though, about whether it might make more sense to use your main smartphone as a mobile hotspot. Upgrading that plan to give you more data can sometimes be cheaper than buying a separate data-only plan.

What should you look for in a data-only SIM?

Easy. It’s all about getting the most data for a given budget, or a specific amount of data for as little as you can. If £24 will get you 30GB with one network but 40GB with another, then the second is giving you a better deal. In fact, the five biggest providers offer similar packages at similar prices, but there are some bargains if you look around.

Note that prices may differ depending on the length of any contract, so make sure you’re comparing 12-month contracts with 12-month contracts, or you could find yourself signing up to a slightly cheaper contract that locks you in for longer.

Otherwise, you need to look at coverage and speed. We use data from RootMetrics to get a solid idea of the 4G speeds available on different networks, but it’s also well worth checking what kind of coverage you can expect where you live and work and the maximum speeds you might realistically receive. All of the networks have their own coverage checkers which you should use before signing up.

Finally, take a good look at any roaming features, particularly if you plan to use your tablet or device abroad, and see if there are any terms and conditions that might affect your use. While it’s becoming less common, some data-only plans were once restricted to tablets only, meaning they weren’t designed to work with a smartphone or modem and you were breaking the contract if you used them outside a tablet.

How much data do I need?

It depends what you need to do. If you’re just using email, checking social media and doing some casual browsing, you might be able to get away with 5GB or even 2GB per month. If you’re a heavier user, 10GB to 20GB might be sensible. Be careful, though. It’s easy to use huge amounts of data browsing or streaming video on a tablet or a laptop, and you could easily burn through 100GB in a couple of weeks of Netflix bingeing. Don’t even think about downloading and playing big online games.

What about PAYG?

You might not need to use your laptop, tablet or mobile broadband router every month, in which case you could look at getting a data-only SIM on a one-month contract or opting for PAYG. These tend to work out more expensive over prolonged use but cheaper if you only need a lot of data sporadically, perhaps for a holiday, business trip or while moving house. After all, why sign up for a year of £22 payments if you’re only going to need 20GB or so for a month.

Read next: The best PAYG SIM deals

The best data-only SIM deals of 2019

Three: The best value data-only deals

Price when reviewed: From £7.50 per month | Buy now from Three

Three takes mobile broadband seriously, so it’s no surprise to find that it has the cheapest data-only deals in town. Whether you’re looking for a basic 2GB allowance or a more generous 15GB, Three undercuts the competition by a pound or two. Pay more and you’ll find that Three gives you more data at any given price point. While spending £25 with Vodafone or £27 with EE will net you 30GB, £24 with Three will buy you a whopping 40GB. What’s more, Three is the only network to go all the way up to 100GB, although it’s going to cost you £26 a month.

Better still, these prices all assume a 12-month contract. Sign up for 24 months in advance and each shrinks by £2. Conversely, pay month-by-month on a rolling one-month contract and the prices rise.

The only thing that counts against Three is that, while coverage is excellent, speeds aren’t generally as good as you’ll find on EE or Vodafone. The last RootMetrics survey placed Three third for both speed and data connectivity, with a UK aggregate median download speed of 13.6Mbits/sec. That’s still fast enough for most applications, but if performance is your be-all and end-all then paying more for a super-speedy service might make sense.

Buy now from Three

EE 4GEE data-only SIM: The best data-only plans for high-speed connectivity

Price when reviewed: From £12 per month | Buy now from EE

RootMetrics’ latest test results place EE as the fastest mobile network in the country, with an aggregate median download speed of 37.6Mbits/sec, and with speeds of over 40Mbits/sec available in four of the UK’s 16 major metropolitan areas. In all but one of the remainder you can expect speeds of over 30Mbits/sec. These speeds will be inflated by EE smartphone users with the firm’s fastest 4G plans, but if you want to make sure you’re getting the fastest connection in most parts of the UK, nobody else comes close.

Admittedly, you have to pay extra for the privilege. EE’s 12-month contract data SIMs start at £12 for 5GB and go up to £39 for 50GB, making it substantially more expensive than Three and a little pricier than Vodafone. If you want a data SIM for simple browsing or a little light work on the road, the speed difference probably isn’t worth it, but if you hate the wait every time a page loads or want near-instant streaming, then EE has the data-only deals for you.

Buy now from EE

Vodafone: Good data deals and speeds at decent prices

Price when reviewed: From £11 a month | Buy now from Vodafone

Vodafone sits in a sweet spot between its big rivals EE and Three. On the one hand, it’s a little cheaper than EE, giving you 30GB for £25 or 50GB for £30, where they would set you back £27 and £39 with EE. On the other hand, it’s faster than Three. In the last RootMetrics UK mobile network report, it was placed second to EE in terms of data connectivity and speed, with a UK-wide median download speed of 21.7Mbits/sec. Moreover, where Three couldn’t deliver median download speeds above 20Mbits/sec in any major metropolitan area, Vodafone managed it in eleven out of sixteen – with speeds of over 30Mbits/sec in six of those.

The choice really comes down to how much data you want and how much you value speed. At the lower 5GB and 15GB capacities, there’s only a pound in it between Vodafone and EE, while Three only gets a lot cheaper once you reach 20GB and above. Looking for the best balance between data allowances, price and speed? With Vodafone you might have found it.

Buy now from Vodafone

BT Mobile: Great mid-range data deals

Price: From £15 | Buy now from BT Mobile

At first, it seems hard to recommend BT Mobile. It runs on top of EE’s network, but doesn’t offer the same maximum speeds as EE, while Three and Vodafone offer better value either at the low-end or the high-end of the price range. Zero in on the middle range, though, and you’ll find that BT gives you 8GB for only a little more than Vodafone charges for 5GB and a little less than BT charges for 10GB. It also matches both pound for pound on its 15GB data deal.

That’s worth noting because, while BT Mobile won’t give you EE’s top speeds of up to 60Mbits/sec, you’re still getting access to the UK’s fastest network with speeds of up to 30Mbits/sec. As a bonus, you can also use BT’s UK-wide network of over five million Wi-Fi hotspots at no extra charge. If you’re looking for a speedy network with a reasonable 15GB allowance, your £20 a month is best spent here.

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EE 4GEE: The best PAYG data SIMs

Price when reviewed: Free PAYG SIM with add-ons from £2 | Buy now from EE

Curiously, while EE is one of the pricier networks for monthly data, it’s the cheapest on PAYG. Send off for a free PAYG 4GEE data SIM and you can spend as little as £2 on a 30-day add-on, albeit for a miserable 200MB. A more realistic 2GB could be yours for just £7, while 20GB is a reasonable £25. With some decent options in-between you can buy what you need as and when you need it.

EE also has you covered if you need add-ons with a longer validity. A 90-day add-on starts at £17 for 6GB and goes all the way up to £44 for 30GB. This turns out to be a cheap way to get 10GB per month (at just under £15 per month once you break it down), making EE’s PAYG option something of a hidden bargain.

Buy now from EE

Three PAYG: Great PAYG Data SIMs for long-term use

Price when reviewed: From £10 per month | Buy now from Three

Three doesn’t just have the cheapest data-only monthly contract deals, it also wins on data-only PAYG, especially if you want your pre-paid allowance to last you a long time. You basically get four choices. The most basic £10 option gets you a SIM pre-loaded with 1GB of data, valid for 30 days, and when you top it up you get an extra 200MB every month. Above that, the £16 +3 SIM brings you a SIM preloaded with 3GB of data valid for three months.

Need more with a longer use-by date? The +12 SIM has 12GB valid for 12 months, while the +24 SIM has 24GB for (you guessed it) 24 months. This arguably makes more sense as an annual purchase, as if you’re only using roughly 1GB every month, you’re only paying £5 a pop.

Buy now from Three