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Various logos of UK mobile networks

Three's unlimited data SIM only deal:
get it for £20 a month

Three phone and SIM card

The retailers featured on this page may compensate us when our readers follow links to their websites and make a purchase. More

We look at the benefits and any restrictions on Three's £20 unlimited data SIM only plan to see if it's truly unlimited. Here's what we found. SIM Sherpa is your trusty guide. Last updated: October 25th 2019.

What's the deal?

Unlimited everything for £20 a month  (4.5/5)

Three SIM card

It's unlimited data. And it's priced at £20 (if you're willing to commit to a 24-month contract). There is no cheaper unlimited everything SIM on the market.

Plus you get Three's usual benefits of 99% 4G population coverage, inclusive roaming and perks like free easyJet upgrades and their daily rewards app, Wuntu.

Useful link: Read full benefits below

Unlimited
minutes
+
Unlimited
texts
+
Unlimited
4G data
=
£20 a month
on a 24-month contract
(opens in new tab)

Or it's £1 more if don't want to commit to such a long deal:

Unlimited
minutes
+
Unlimited
texts
+
Unlimited
4G data
=
£22 a month
on a 12-month contract
(opens in new tab)

What's good about it?

It's genuinely unlimited data - and that's pretty rare

Three offer banner

On a 24-month contractSee full offer

at Three.co.uk
(opens in new window)

If you've ever put your phone down because you're worried about going over you data usage limits, Three's unlimited data SIM puts an end to that. You're free to use as much as you like in the UK at no extra cost.

And you're not limited by any sneaky traffic management or throttling rules when you use it in this country either. Others sometimes promise no data caps but then slow you down to stop you using too much.

You can also use it for tethering (personal hotspot), which is where you connect tablets or laptops to your phone so they can access internet anywhere you have mobile signal. That's unlimited in the UK too.

The only restrictions come when you're using your SIM abroad. There, you won't be able to use tethering, a monthly cap of up to 19GB applies (depending where you are) and Three reserve the right to slow down your connection while roaming.

If you managed to use 1000GB in a month, Three say this might trigger them looking into whether you're definitely using the SIM for just personal use (you can't use the SIM for commercial purposes).

That doesn't mean you can't use that much. And it's not an actual fixed limit. It's just the point at which Three might look into your usage.

Useful link: Read Three's terms and conditions

Three's network offers good 4G coverage and speeds

Three's network map

Make sure you'll be able to use unlimited dataCheck Three's coverage

at Three.co.uk
(opens in new window)

It's true that Three aren't the UK's largest network but their 4G now reaches 99% of the population in the places where they live. There is still work to do in rural locations. The deal gets you 5G for no extra cost when it launches too.

We'd always recommend checking any network's coverage before you sign up. Use Three's official network map here to do so. Be sure to look not just at home but anywhere you'll be using your phone.

Over 4G, we'd expect Three customers to get download speeds of around 20 Mbps on average, which currently puts them just behind Vodafone and a way off EE.

This is a healthy score that is similar to what many will be getting home over non-fibre broadband. It'll support smooth video and audio streaming and let you browse the general internet

Useful link: Check Three signal in your area

The £20 / £22 prices beat Three's competition quite easily

Vodafone's unlimited data plan banner

We do rate Vodafone's Unlimited Max planSee the plan

at Vodafone.co.uk
(opens in new window)

It's rare to see Three offer the deal for less than £20

Three's Black Friday offer banner

The offer was Three's Black Friday deal tooSee new offers

at Three.co.uk
(opens in new window)

We closely monitor Three's pricing on their unlimited data deal. And £20 has been pretty much the established price for the whole of this year, first on the 12-month contract and later on the 24-month.

For a good part of this year, the 24-month contract was available with 6 months half price. But that offer ended on 24th October. During the offer the 12-month deal was priced at £20 but full price.

So the basic price is never lower than £20 a month. You just might occassionally get some free months here and there. We'll update this page when you do.

Useful link: See Three's SIM only deals page

SIM Sherpa can help you find your next SIM only deal

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