This unlimited data SIM only deal on Three is the cheapest we've ever seen

Three Unlimited SIM only deals
(Image credit: Future)

Three's unlimited data SIM only deals are the best value offers in the UK right now. But unlike last weekend, the best place to get them today isn't direct from Three. And if you didn't pick up last week's deal, we've got even better news for you, you'll pay even less today.

SIM only deals are ideal for people happy with their current phone who are now (or soon to be) out of contract. Or if you've had your eye on a new phone and just want to pay for it upfront yourself without it being attached to a contract, this is the way to go.

There's no doubt about it, this is the best SIM only deal we've ever seen for unlimited data (you get unlimited minutes and texts too of course). Specialist mobile retailer is selling the SIM for just £18 a month and giving you £40 automatic cashback. This is a much more flexible 12-month contract instead of the 24-month one Three was running last week too.

The cashback is 'guaranteed' instead of the pesky 'by redemption' offers we sometimes see where you have to manually poke the network/store once every few months, sometimes by post. None of that here, £40 will be transferred into your bank 99 days after connection.

So instead of a total contract cost of £216, you actually end up paying just £176 over the course of 12 months. And when you think of it that way, that monthly cost effectively whittles down to more like £14.66 a month - there's never been a better deal.

Compare it with last week's deal at £16 a month, with no cashback and that annual cost was £192, but seeing as that was a 24-month contract instead of 12 like this one, you were in it for the long haul and a £384 total cost.

SIM only deal of the week

Three SIM only | Unlimited data, minutes and texts | £18 per month at

Three SIM only | Unlimited data, minutes and texts | £18 per month at
After 99 days you'll get £40 cashback transferred automatically into your bank account. Even without the cashback, this is a stunning price for Unlimited data from the UK's best big data (and 5G-ready network). Take a look at our comparison article at the bottom of this article if you'd like to check out other options.

Unlimited data really does unleash your phone's capabilities and you'll never have to worry about going over your allowances and incurring a hefty bill again. Apps like Netflix, YouTube, Spotify, Instagram, Snapchat and Facebook can really chew through your allotted gigabytes nowadays, so not having to curb your streaming, downloading and browsing is a real eye-opener, especially if you regularly find yourself away from Wi-Fi's sweet embrace. An unlimited data SIM only offer is great if you want to create a hotspot for your laptop or tablet to connect to when away from home too. 

And if you're thinking of picking up a 5G-ready phone, this SIM only deal is ideal as the Three network is the biggest provider of the new superfast signal that frankly blows 4G out of the water.

Why else choose a Three SIM only deal?

In addition to that unbeatable price per gigabyte (we've checked), Three has one of the widest-reaching networks in the UK and of course, you can port over your existing phone number. And like we said earlier, if you're thinking of picking up a 5G phone anytime soon, Three is the biggest 5G provider in the UK and these SIM only deals mean you're 5G-ready too.

Want to use your phone abroad? Of course, you can use your allowances in Europe, but that's fairly standard across most data providers now. However, Three users also get coverage outside of the EU without having to pay for an additional bolt-on. We're talking prime holiday destinations too like the USA, Australia, New Zealand, Singapore, Brazil, Peru, Hong Kong and more.

Still not convinced? Check out our comparison chart below to see what other SIM only deals are out there today. If you can get by with less data (and many users can), you can get cheaper deals with a decent amount of gigabtyes too. If you're in the market for a new mobile too, check out our list of the best gaming phones for some inspiration. And if you'd like to top of your security and privacy options on all your favourite connected devices, be sure to take a quick look at our roundups of the best antivirus and best VPN.

Brendan Griffiths

Brendan is GamesRadar's former Managing Editor of the Hardware & eCommerce team. He also spent time as the Deals Editor at our sister site, TechRadar. He's obsessed with finding the best tech, games, gadgets, and hardware at the lowest price. He also spends way too much of his free time trying to decide what new things to watch on Netflix, then just rewatches It's Always Sunny in Philadelphia instead. Nowadays you'll find him as the eCommerce Content Director for Future's mobile tech sites, Android Central, iMore, and Windows Central.