Best SIM-only deals: Our pick of the best SIM-only deals in the UK this month

With so many options to choose from, finding the best SIM-only deals in the UK can be both tiresome and confusing. With more and more people choosing to go for a SIM-only plan these days, we’ve done the heavy lifting to find you the best deals currently available in the UK this month.

As you can see from our quick list of SIM-only deals below, you can find deals for cheaper than a tenner, but you’ll notice that you get more data and benefits if you’re willing to stretch your budget a little.

Given that the UK is blessed with multiple mobile service providers, you’re sure to find a deal that suits your preference where it comes to price, data, speed and even additional benefits like free social media and streaming, or rolling over any unused data to the next month.

In general, spending a little more money will result in more value for money, but if you’re going to be indoors most of the time or don’t use your data as much, then you should be able to find a good deal without breaking the bank. A £10 SIM-only deal gets you an average of 10GB data, which will easily cater to all your needs when you’re outside the Wi-Fi confines of your home network.

This page is divided into different sections. We’ll start off with an at-a-glance list of the best roundup at the bottom. Next, we’ll tell you what you need to look out for when choosing the best SIM-only deal for you. Finally, we’ll list the best SIM-only deals in 10 different categories this month.

Best SIM-only deals in the UK: At a glance

  1. Best no-contract deal: Smarty (30GB for £10)
  2. Best for unlimited data: Three (Unlimited data for £18/mnth)
  3. Best for free social media and video streaming: Voxi (12GB for £12/mnth)
  4. Best for reliable network speed: EE (150GB for £20/mnth)
  5. Best deal for roaming: Vodafone (Unlimited 5G data for £30/mnth)
  6. Best deal with freebies: O2 (Unlimited data for £30/mnth)
  7. Best for free calling abroad: Lebara (15GB for £15/mnth)
  8. Best budget SIM-only plan: Smarty (4GB for £6/mnth)
  9. Best for Sky customers: Sky Mobile (12GB for £10/mnth)
  10. Best for BT sport: BT Mobile (50GB for £20/mnth)

How to choose the best SIM-only deal for you

What is a SIM-only deal?

A SIM card is the small chip that you insert into your phone to tell it who you are and what mobile phone plan you are on. It stands for Subscriber Identity Module and is used to authenticate the user’s information, including a special number that identifies the phone on the network.

As the name suggests, a SIM-only plan covers the cost of the SIM – and therefore the cost of being on the network – but not the phone it slots into. That means you’ll need to provide your own handset, whether that’s a case of buying it outright or using a previously owned smartphone.

Because you’re only paying for the SIM, these contracts tend to be substantially less expensive than their phone counterparts. This makes sense, given that you’re not paying off the price of the handset in addition to the network costs.

Pay monthly or Pay As You Go?

In this guide, we’ll be covering monthly SIM-only contracts, but it’s worth mentioning the alternative: Pay As You Go. With these plans, there’s generally no contract and therefore you’re not tied into a given time period with the network provider. Instead, you get a certain amount of minutes, texts and data, and when you run out you can ‘top up’ your SIM card by choosing to pay a set fee.

We’d recommend a Pay As You Go Plan if you don’t think you’ll be using your phone much, at least not so much that you’ll regularly go through the allotted minutes, text and data within a month. If you do, you won’t necessarily be saving any money over a monthly plan. Essentially, the benefit of a Pay As You Go plan is flexibility; not being tied to monthly payments for 12 or 24 months. But that benefit falls away if you end up making monthly payments anyway, probably for a smaller data allowance.

What to look out for when buying a SIM-only deal

Data offerings

There are SIM-only deals with limits on minutes and texts, but these days many plans tend to be unlimited in these regards. Instead, the crux of a contract is in its data offering. How much data do you get access to each month? Does the plan have a limit on its data speed?

With the first question, one key thing to consider is how much data you actually need on a monthly basis. An “unlimited” data plan might bring peace of mind that you won’t run out of internet juice, but it might not be the most cost-effective choice if you actually use less than 30GB.

We have some tips on judging the amount of data you need, but a good starting point is to see how much data you currently use, which can be easily done either via your network provider or your phone. You can do this on an iPhone by going to Settings, Cellular or Settings, then Mobile Data. On Android, go to Settings, Network and Internet, Data Usage. See what you currently burn through in a month and use this as a yardstick for judging what your future data needs might be.

In terms of data speeds, this is an easy-to-miss factor that can have a big impact on your overall experience. Vodafone, for example, has a trio of “unlimited” data plans, but the lowest tier (Unlimited Lite) has a maximum download speed of only 2Mbps. So while it might not have a cap on overall data usage, this is essentially a cap on the speed you can hope to achieve when using your phone. As a point of reference, Netflix recommends a minimum download speed of 3Mbps for HD streaming.

Contract length and lifetime cost

Besides data, the next thing you’ll be keeping an eye on is the length of the contract you’re signing up to. Some last 24 months, while others only last 12. If you think you’ve found a good deal, you may want to consider locking it in for a longer period of time. Alternatively, if you like the flexibility of being able to change providers, a shorter plan may be for you. Remember, since you’re not paying off the cost of a handset, your contract will only be paying for the minutes, text and data plan you’ve picked.

The lifetime cost is the total amount you’d spend over the contract length, and it can be a great way to judge the brutal reality of whether or not you’re saving money. Take a few minutes to plot out the amount you’d spend across the 12 or 24 months for different plans, and compare the results. Some SIM-only contracts might be half price for the first six months, for example. That’s great, except for when the monthly cost skyrockets after that period. Does it even out in the end, or do you actually end up spending more?

Another important thing to consider is the cost of the handset. This will very much depend on your particular situation, but if you’re buying a phone outright you’ll want to factor in that cost when calculating the lifetime total. In a nutshell: is the cost of the handset plus the lifetime cost of the SIM-only contract cheaper or more expensive than the lifetime cost of a monthly phone contract?

Benefits and freebies

Finally, some providers will dangle bonuses to try and tempt you into certain contracts. Sometimes these can be good deals, often they will be a tactic to convince you into a more expensive contract. That’s not to say you should avoid a tantalising freebie, only to look at it through the lens of your lifetime cost.

EE, for example, offers a number of “smart benefits” as part of select contracts. These range from access to Apple TV+ or BT Sports Ultimate, to bonus “free” roaming destinations. Are these things you would actually want to buy otherwise? Taking the freebies out of the picture, would you opt for the contract without them? Added extras might sweeten an already good deal, but just remember to look at them critically as part of an overall balance of costs.

The best SIM-only deal in the UK in August 2021

ID Mobile: Best deal for data

Price: 100GB for £8.50/mnth (after cashback) | Get this deal

Lesser-known network ID Mobile is currently offering a whole host of tempting SIM-only plans— especially if you want plenty of data. For instance, you can get 50GB data for just £9/mnth on a one-year contract, after cashback. That said, if you’d rather avoid committing to a long term contract, you can get Unlimited data for £20/mnth on a one month contract.

On top of this, there are multiple packages that give you unlimited data, ranging from 1-24 months. All ID Mobile’s deals come with unlimited minutes and texts and you can also rollover any unused data to the next months, meaning you can easily accumulate data for when you need it the most— many of them are limited-time deals though, so move fast!

Key details – Contract length: 1 – 24 months; Total price over contract: £6 – £360; 5G-ready: Yes; Freebies: Rollover unused data; Free roaming in 50 destinations

Buy now from

The best SIM-only deals in the UK in August 2021

1. Smarty: The best no-contract deal

Price: 30GB for £10/mnth | Get this deal

Smarty might be a lesser-known name but it has several Uswitch awards under its belt, including Best PAYG Network and Best Value SIM. Running on Three’s network, it has one of the best offers this month giving you a generous 30GB for a tenner. Better still, is the flexibility to cancel your contract at any time.

Key details – Contract length: One month; Total price over contract: £10; 5G-ready: No; Freebies: Personal Hotspot

Buy now from Smarty

2. Three: Best deal with unlimited data

Price: Unlimited data for £18/mnth | Get this deal

Three are offering unlimited data for just £18 a month on a 24-month contract. As well as unlimited data, it also comes with unlimited texts and minutes, is “5G ready” and also works with Three’s “Go Roam” scheme that gives you free roaming in more than 50 countries – perfect if you’re planning that long-awaited holiday.

Key details – Contract length: 24 months; Total price over contract: £432; 5G-ready: Yes; Freebies: Personal Hotspot, Free roaming in 71 destinations

Buy now from Three

3. VOXI: Best deal with free social media and streaming

Price: 12GB for £12/mnth | Get this deal

Most of us use our mobile data to browse social media websites or access streaming services like YouTube, Netflix and Amazon Prime Video. Voxi has a brilliant solution because it offers free social media browsing and streaming service usage. Its network is provided by Vodafone to ensure reliable 4G or 5G coverage. But best of all, the monthly data allowance on a couple of its deals have seen massive boosts.

Key details – Contract length: 30 days; Total price over contract: £12; 5G-ready: Yes; Freebies: Unlimited video streaming and social media, free EU roaming in 47

Buy now from Voxi

4. EE: Best for reliable network speed

Price: £150GB for £20/mnth | Get this deal

EE has consistently been voted the best mobile network in the UK. You can currently grab a hefty 150GB of monthly data from EE for £20/mnth as part of the provider’s 5G plan. For most people, this is as good as unlimited data because you’ll be hard-pressed to use up that much data unless you stream content every day outside the confines of Wi-Fi.

Key details – Contract length: 24 months; Total price over contract: £480; 5G-ready: Yes; Freebies: 6 months Apple Music and 3 months BT Sport

Buy now from EE

5. Vodafone: Best for roaming

Price: Unlimited 5G data for £30/mnth | Get this deal

Vodafone has the best offering when it comes to roaming. Its £30/mnth Unlimited data deal lets you use your phone in 81 countries, which beats Three’s offering by 10 more countries. This is great if you tend to travel a lot because it means you won’t have to worry about using your phone abroad.

Key details – Contract length: 24 months; Total price over contract: £720; 5G-ready: Yes; Freebies: 51 roam-free destinations; 3-month free trial of SecureNet

Buy now from Vodafone

6. O2: Best SIM-only deal for freebies

Price: Unlimited data for £30/mnth | Get this deal

O2 has a platter of SIM-only deals, with this one including up to six months free Apple Music and a choice of six months of either Disney+, Amazon Prime Video, Amazon Music or others. For reference, Apple Music costs £9.99/month and Disney+ costs £7.99/month so that itself comes to just over £30 in savings.

Key details – Contract length: 24 months; Total price over contract: £480; 5G-ready: No; Freebies: 6 months Apple Music; 6 months Disney Plus; Free roaming in 75 destinations

Buy now from O2

7. Lebara Mobile: Best for free calling abroad

Price: 15GB for £15/mnth | Get this deal

If you have friends and family living abroad, then this deal from Lebara (which runs on Vodafone’s network) is a great way to keep in touch with them. Not only is it contract-free, but you get unlimited international minutes free to over 40 countries, covering the USA, Australia and a large portion of Europe and Asia.

Key details – Contract length: 30 days; Total price over contract: £15; 5G-ready: No; Freebies: Unlimited international minutes to 41 countries

Buy now from Lebara Mobile

8. Smarty: Best budget SIM-only plan

Price: 4GB for £6/mnth | Get this deal

This deal from Smarty is the cheapest one available at the time of writing and a great offering if you’re mainly at home and only use your smartphone sparingly. That said, you still get unlimited calls and texts, so if don’t mind having a small amount of monthly data (only 4GB), then this deal is definitely worth looking at! If that’s not quite enough data for you, then for an extra £1 a month you can get 8 GB. 

Key details – Contract length: one month; Total price over contract: £7; 5G-ready: No; Freebies: None

Buy now from Smarty

9. Sky Mobile: Best for Sky customers

Price: 12GB for £10/mnth | Get this deal

Sky TV is considered to be one of the best UK TV service providers. Their basic packages start at £25/mnth, but this gives you access to the entire gamut of channels. The benefit of choosing Sky Mobile is that you can stream Sky content on your mobile without eating into your monthly data allowance and any unused data is rolled over to the next month. What’s more, its 12GB plan is currently down to £10, from £12.

Key details – Contract length: 12 months; Total price over contract: £120; 5G-ready: No; Freebies: Unlimited streaming on Sky apps; Unused data is rolled over

Buy now from Sky Mobile

10. BT Mobile: Best for BT sport

Price: 50GB for £20/mnth | Get this deal

If you’ve already got BT broadband, then you can get £5 off this contract, bringing the price down to just £15. It includes 50GB data, unlimited minutes and texts, and BT will throw in their BT Sport app, meaning you can stream all your favourite sport on the go. The app alone is worth £10 per month, making this an amazing deal if you use BT sport.

Key details – Contract length: 24 months; Total price over contract: £480 (without BT broadband)/ £360 (for BT broadband users); 5G-ready: No; Freebies: BT Sport app (worth £10/mnth), Data roaming in 47 countries

Buy now from BT

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