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Cheapest 5G Sim-only deals 2021

Discover the best deals for high data users or those want to spend just a few pounds a month, including offers from Giffgaff, O2 and Three

Cheapest 5G Sim-only deals 2021

With 5G now becoming more standard in even cheap mobile phones, and more providers offering 5G data in 2021, it’s never been more tempting to get involved.

Fortunately, there are a range of deals available that can making picking up a 5G Sim a no-brainer, whether you’re a high data user or just fancy a more responsive browsing experience.

Below, we’ve rounded up some of the best deals you can find, for low, medium and high data amounts to suit all mobile users.


Discover the best and worst UK mobile networks, or use Which? Switch Mobile to find the best Sim-only deals on a wide range of providers.


Best 5G Sim-only deals

Low data 5G deals (less than 5GB)

These deals are best for those who do not often use mobile data or only use mobile data for light activities such as web browsing and light social media usage. All come with unlimited minutes and texts.

Medium data 5G deals (5GB – 10GB)

Opt for a bit more data if you sometimes watch videos use social media heavily when out and about.

High data 5G deals (over 10GB)

These deals are for those who play online games, watch a lot of videos and regularly use and upload to social media when out and about.

Unlimited data 5G deals

These deals are great for those who wish to tether or otherwise use their phone extensively and do not want to worry about how much data they are using. Unsurprisingly, Three dominates here as the most cost-effective unlimited data Sim provider.


5G phones are no longer expensive – in fact we have found Best Buys for under £300. Browse our 5G phone reviews for more.


What are the benefits of 5G?

The two main benefits of 5G are speed and capacity. 5G can handle a lot more than 4G and can do it faster. This has the potential in future to be transformative, for example, with internet-connected products and driverless cars, to name a couple of use cases.

For now, this means you can stream higher quality content, play games easier and generally have a better mobile data experience, in theory.

For more, read our guide to 5G. You can also find out more about the rumours surrounding 5G.

What about coverage?

One thing you’ll want to look into before you shell out is 5G coverage in your area.

Our mobile networks coverage map includes information about 5G coverage where you live as well as 4G coverage for all four major mobile networks (EE, O2, Three and Vodafone), which all other networks piggyback off.

Get to know your new provider

Before you switch, it’s worth looking into your new provider to make sure they tick the boxes. We regularly survey customers of 13 major mobile networks to find out their views on everything from customer service and ease of contacting the provider. Read our detailed mobile provider reviews for more.

Should you stay or should you go?

If you’ve found a deal that you like, but you’re otherwise happy with your provider, you might be a bit reluctant to switch. You could try haggling with your mobile provider to see if they can match or better the deal, but if they won’t, switching might be your best option. Fortunately, it’s pretty easy to do – our guide on how to switch mobile network provider explains how.

Our guide to getting the best Sim-only deal includes regular roundups of the hottest deals around. Thinking of changing broadband provider? Our guide to the best broadband deals can help with that, too.

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