The best Three SIM only deals and plans in May 2024

Three SIM only deals are an excellent choice and one of the most popular options on the market right now. Blending affordability with big data plans, Three stands out as the options for heavy data users.

One of the four main networks for SIM only deals, Three utilises its own network, has one of the best 5G rollouts so far and is frequently the cheapest option when it comes to unlimited data SIM only deals.

That makes Three an excellent choice if you're looking to get a 5G SIM-free phone up and running, ready to go all out on streaming, gaming, massive downloads and lots more.

And the good news is that Three SIM only deals have been especially good recently. The network has been slashing prices left, right and centre. The standout offer being a 100GB 5G SIM for just £12 a month - the cheapest price...well, ever.

While there are cheaper SIM only deals out there from some smaller networks, Three seems to fit in as the cheapest of the four main providers - EE, Vodafone amd O2 being the other three.

If you're set on Three as a network then this will be easy! Simply use our price comparison service below to compare the best prices. If you want to learn more first, this guide is filled with information on Three's benefits, how to switch and more.

What is the best Three SIM only deal?

Right now, Three's best SIM plan has to be its 100GB data offer for just £12 a month. This is not only the cheapest unlimited SIM around but also the lowest price ever for an unlimited 5G SIM!

If that is more than you'd like to pay, Three's 8GB for £8 a month plan is also excellent value, halving your bills compared to the above option. However, this may prove to be too little data for some.

Why choose the Three network?

Three SIM only deals

(Image credit: Three)

Is Three a good network?

Three is one of the four main networks. That means it runs its own network and coverage, having total control over its hardware. Launching way back in 2003, the network has had a long history.

It has won multiple awards from the likes of USwitch, YouGov and us, cementing its position as one of the best networks around.

What kind of coverage does Three get?

Currently, Three covers about 99.8% of the UK population. However, that is just for 4G, as far as 5G goes, that number is currently much smaller and you'll have to be in specific areas to get it - mostly city centres.

If you want to see what Three's coverage is like where you live, you can use Three's coverage map to find out more and even see what coverage will be like for your specific phone.

What benefits does a Three SIM offer?

All of Three's plans come with unlimited calls and texts and are 5G ready. Three also offers a strong roaming promotion, allowing you to use your calls, texts and data in 71 different destinations.

Three used to have two other added benefits - Go Binge and the Wuntu app. Go Binge was a service that allowed you to stream from certain apps like Netflix without using data and Wuntu was a rewards app, similar to O2 Priorities or Vodafone's VeryMe.

Is Three a 5G network and do you have to pay more for it?

Yes, Three is now a 5G network and has been for quite a while. It is now joined by almost every single other network as 5G rapidly rolls out with just a few exceptions.

So far, Three has had one of the best rollouts offering 5G in a wide range of cities and towns and having some of the fastest speeds and best latency.

The other benefit of Three's 5G is that unlike some other networks, it doesn't cost you any extra, it is simply added in on every plan. 

How to switch to a Three SIM:

Three SIM only deals

(Image credit: Future)

How do you switch to Three?

Firstly, you need to know you're eligible to switch plans. If your contract still has a few months until it ends, you are likely to be charged for the remaining time meaning it is usually best to fully finish your contract first.

Switching and keeping your number:

Once you know when your contract is finishing and you've got your new deal, you need to decide if you want to keep your number. If so, you can request a PAC code (Porting Authorisation Code) from your old network. This can be done via the phone or through a text.

Then you simply get in touch with Three and give it your new code.

Switching with a new number:

Don't want to keep your number - it's even easier! Simply get in contact with your new provider and tell them you want a new number and tell your old network your ending your contract.

This can also be done via a text to switch service. Simply text STAC to 75075.

What SIM card do I need?

SIM cards these days fall into three sizes and these are: Standard, Micro and Nano, descending in size. More on eSIMs below. If you're ordering your SIM only you'll likely find it arrives in a credit card sized piece of plastic out of which can you pop your microchip SIM.

A standard SIM measures 25 x 15mm and was used in phones before 2010 and a few after then.

The Micro SIM stands at 15 x 12 mm and was used in phones from 2010 and you'll still find some phones work with these now.

The Nano SIM, introduced in 2012, measures in at 12.3x 8.8mm and is the most commonly used SIM in phones.

The Combi SIM might be what you get sent by a SIM only provider as it contains all three sizes, and you push out the one that fits your phone. This is ideal as you don't need to know your size prior to this as you can hold it up to the SIM tray and see.

How much data, texts and calls do I need?

As far as calls and texts go, this isn't a factor you have to worry about with Three. All of its plans operate with unlimited calls and texts - a feature seen on a number of networks. 

When it comes to data, this is a completely different story. Normally you can simply look at how much data you've used in the past and this will be a good measure.

First time you're getting a SIM? These are how the data caps line up with usage:

  • 1GB: A limited option that won't be enough for most. If you rarely use the internet and occasionally need to use Google Maps or check the internet, this can be a cheap option.
  • 5GB-10GB: This is the range most people will fit into. It allows for pretty intensive usage of social media, Maps and internet searches without fear of running over. While you can do a bit of streaming, don't push it and avoid HD!
  • 10GB-50GB: If you like to stream when you're out and about, use maps on a daily basis and generally have a data intensive lifestyle, this will likely be a cap you should be looking in. Keeping under 50GB can keep your costs at a still affordable point.
  • 50-100GB: At this point, you're going to have to be a real data drainer for this to be necessary. Downloading apps on the go, HD streaming, big downloads and working from home.
  • 100GB-unlimited: Unlimited data plans have significantly come down in price over the years and can even be a legitimate alternative solution to having full broadband if you live somewhere with an excellent 4G/5G connection. However, for most people, it's not going to be necessary.

Three's MVNOs:

While Three owns its networks, other providers also use its coverage and speeds. Known as MVNOs (Mobile Virtual Network Operators) these networks "piggyback" off of Three's network to make use of it.

There is three networks that do this but the two most important ones are iD Mobile and Smarty. Both networks operate on 1-month rolling contracts and offer some extremely affordable prices.

Alex Hughes

Alex is a journalist who has written extensively about all things broadband, SIMs and phone contracts, as well as scouring the internet to land you the best prices on the very latest in gadgets and tech. Whether that be with the latest iPhones and Android handsets, breaking down how broadband works or revealing the cheapest SIM plans, he's in the know, and will help you land a bargain.