A SIM only deal is a mobile phone plan that offers calls, texts and data in return for a monthly fee, but does not come bundled with a phone. Leaving the phone out of the equation means SIM only deals can be much cheaper than general mobile phone deals which makes them ideal if you already have a handset or are eyeing up SIM-free phones.

Our handy price comparison tool will help you filter through and compare all of the UK’s available SIM only deals so that you can zero-in on the one that’s right for you. Prices start from £4 per month for a basic plan while GiffGaff’s “unlimited everything” SIM only deals can be had from around £20 if you’re a power user.

• Discover the best sim-free phones your money can buy

Underneath our tool you’ll find our top 10 recommendations for the best value SIM only deals currently available, whatever your needs – ideal if you're thinking to team one up with a brilliant Black Friday handset purchase. And if you're still unsure whether SIM-only is the route for you, our expert advice will help you decide – our all knowing FAQ includes tips on switching your number, the networks that offer free gifts and answers to a host of other questions. 

The best SIM only deals of the week are:

We've run the figures and plucked out the very best sim only deals available in May 2017.  Whether you’re after the cheapest plan possible, want to dig out the best value big data SIM plan or just want an all-round great deal but don’t know how much to spend, you’ll find a recommendation just for you.

1. The absolute cheapest SIM only deal out there

iD Mobile | 30-day contract | 250MB data | 250 minutes | 5000 texts | £4 per month
 This is the cheapest readily available SIM only deal currently available in the UK. If you just need to keep a phone up and running for occasional use, this is a good option. Clearly 250MB is not much data at all so you'd be advised to either keep mobile data switched off or be careful what apps are updating in the background. BUT WAIT, CHECK OUT THE NEXT DEAL FIRST!

View this SIM only deal at iD/Carphone Warehouse

2: The best 1GB+ SIM only deal

iD | 30-day contract | 1.5GB data | 250 minutes | 5000 texts | £5 per month
If you're looking for a super cheap SIM only deal but don't want to limit yourself too much with data, 1.5GB for £5 is the best option out there right now. Especially given how freely wi-fi is available outside of the home nowadays. You'll still be able to access emails, browse the net and casually check Facebook and stay under the limit. And as it's a 30-day SIM only deal, you can change your mind and cancel at any time.

View this SIM only deal at iD/Carphone Warehouse

3: The best 2GB-3GB SIM only deal

iD | 30-day contract | 3GB data | 500 minutes | 5000 texts | £8.00 per month
 The iD/Carphone Warehouse team is really cleaning up with these cheap SIM only deals and has been the go-to store for the cheapest low data deals for a while. If you're prone to viewing a few YouTube videos away from wi-fi, this 3GB option may suit you better than the aforementioned 1GB deal. And iD has just doubled the amount of calls you can make, too.

View this SIM only deal iD/Carphone Warehouse

4: The best 4GB-8GB SIM only deal

Three | 12-month contract | 8GB data | 600 minutes | Unlimited texts | £14 per month
If you can get by with less data, the iD deals above are better value, especially as they're only 30-day contracts instead of 12-months. Plus iD uses the Three network anyway. But if 8GB is what you need and your phone takes micro SIM cards, this is the best deal. Handily, you can use your allowances abroad and you can even use your data to create your own personal hotspot for using laptops and tablets away from wi-fi.

View this 8GB 3 Mobile SIM only deal

5: The best 10GB-16GB SIM only deal

3 Mobile | 12-month contract | 12GB data | 600 minutes | Unlimited texts | £15 per month
If you're happy to sign up for 12 months you can get an excellent deal at just £15 a month for a whopping 12GB of data. You'll also be able to use your data as a  personal hotspot for other devices when away from wi-fi. Plus you can use your allowances abroad! Happy with your phone? This is excellent value for a 12-month deal, especially as Mobile Phones Direct are throwing in a tenner cashback, too.

View this 12GB SIM only deal from Mobile Phones Direct

6: The best 20GB-30GB SIM only deal

Vodafone | 12-month contract | 25GB data | Unlimited calls and texts | £11 per month (after cashback)
This is an impeccable deal from Mobile Phones Direct. For a mere £11 a month, you get a massive 25GB of data and can choose between free access to Sky Sports mobile, Now TV or Spotify Premium. You can use your allowances abroad for free in over 40 countries too! The one small drawback – it's only this cheap by claiming £96 of cashback.

View this 25GB Vodafone SIM only deal available from Mobiles.co.uk

7: The best SIM only deal for unlimited data

Three | 12-month contract | Unlimited data | Unlimited texts | 200 minutes | £24 per month
Sometimes, you've just gotta have all the data. Netflix marathons, epic Pokemon Go quests, constant Spotify tunes, this all you can eat data bundle is ideal for the serious mobile user who never needs to worry about poxy thing like data allowances or wi-fi. Plus you'll get £35 cashback. Giffgaff can do unlimited for only £20 a month, but once you've used 6GB of data each month, it cuts your speeds down from 4G.

Get this unlimited data Three deal

8. Best EE SIM only deal

12-month contract | 3GB data | Unlimited mins and texts | £19.99 per month
Wait! Stop! We know that monthly tariff sounds like a lot (to put it mildly) for only 3GB of data, especially when you compare it to the deals iD can produce. But there's a sweetener here – a £98 cashback sweetener. That's so sweet, it must be bad for you! It effectively brings the monthlies down to £11.99, which isn't bad for EE's super fast 4G speeds.

View this EE SIM only deal at Mobiles.co.uk

9: The best SIM only deal on O2

12-month contract | 20GB data | Unlimited mins and texts | £21 per month
O2 is not a cheap network for SIM only deals, but for many users they can be good value thanks to the O2 Priority program. We've chosen the 20GB deal here as the prices for smaller data bundles are frankly ridiculous. However, every week, you'll be able to take advantage of the O2 Priority app that dishes out discounts and freebies.

View this 20GB for £21 O2 SIM only deal

10. Best 3 SIM only deal

12-month contract | 30GB data | 600 minutes minutes | Unlimited texts | £18 per month
Three is often the go-to network for big data deals and the cheapest of the big networks for a 30GB SIM only deal just got £2 a month cheaper. It's a shame they're only sticking 600 minutes in instead of unlimited, but that should be enough for most users, especially when you can use data-driven apps like WhatsApp to make calls instead. Plus, Mobile Phones Direct is throwing in £15 cashback.

View this 30GB 3 Mobile SIM only deal from Mobile Phone Direct

Should I go SIM only?

If you a) want to save some money; b) don't want to be tied into a lengthy contract; or c) both of the above, then SIM only is well worth considering. In fact, you're probably one of two people if your thoughts are indeed turning to SIM only:

1. You're coming to the end of your contract and your network is calling you a million times a day to get you to upgrade. Well if your phone is dying a death or you just fancy a change, head to our best mobile phones deal page to see what bargains are lurking, but otherwise going SIM only on your current phone is a no-brainer. You'll wind up paying much less than you are under contract, and you can stick to a rolling 30 day contract so that if your circumstances change, you can get out of the arrangement tout suite.
2. It's time for a shiny new smartphone and you want to get the best value humanly possible. You'll have to find a few hundred quid up front for the handset (be sure to check our SIM free comparison chart) but box clever and you'll end up paying less over the next 24 months (see below). Plus, if you're a commitment-phobe, most SIM-only plans don't require you to sign up for two years like you would with a normal contract.

Is SIM only cheaper than contract?

It certainly can be. In fact, teaming a SIM only plan with a standalone handset could save you a packet. Take the new Samsung Galaxy S8 as a prime example. You'll have to pay at least £689 upfront, but combine that with iD's fiver a month 1.5GB deal and you'll end up paying £809 over two years – that's over £100 cheaper than the cheapest 1GB contract from a major network.

Not all the savings you can make are as extravagant, and on big data it's frequently more cost effective to dive into a contract instead. But if you can afford to splash a few hundred pounds up front then the savings over the next couple of years could well be worth it – especially if you can bag a bargain on Black Friday 2017.

Is my phone unlocked – can I use a new SIM in it?

The times have passed since most phones were locked to a network and you had to pay a dodgy backstreet 'engineer' to unlock it. Nowadays, it's standard practice for networks to let you use whatever SIM you want in the phone as soon as you've paid up the original contract (or earlier if you pay them a fee) – and Three ships all its handsets unlocked from the outset.

The exception, alas, is Apple iPhones. They're generally sold locked to the original network that you purchase them with for the life of the handset. Very frustrating if you're looking for a tasty SIM only deal once your 24 month sentence is up.

The good news is that your iPhone (or any other mobile before the end of your contract) can be unlocked – the bad news is that most networks make you pay for the privilege. Insert a friend or family member's SIM into your phone to see whether it's already unlocked and, if it isn't, look for your network below to see how to cut ties with them:

• EE Once six months have gone by on your contract, you can call EE on 0800 956 6000 and pay them £8.99 to unlock your phone. It says it will take around 10 days to complete. PAYG phones can be unlocked for free.
• O2 As long as you don't own a Samsung Galaxy S8 or S8 Plus (they can't be unlocked until you've paid off your contract), you can unlock any O2 phone – including iPhones – for free if you're on a pay monthly contract. PAYG customers have to pay £15.
• Three Fear not, all phones on Three are unlocked as standard. Shove whatever SIM you like in there, it will work a treat.
• Vodafone The red network doesn't quite get the same marks as Three, as your phone will be locked to them on arrival. But they have made unlocking handsets absolutely free within 10 days of your request.

What SIM card size do I need?

There are three sizes of SIM card that you can get for your phone, and the one you need will depend on your handset. It's been a while since the traditional, so-called standard SIM (15x25mm) has genuinely been the staple in new phones. Instead, any phone you've bought within the last five or so years is much more likely to require a micro (12x15mm) or nano (8.8×12.3mm) SIM – the iPhone 5 was Apple's first mobile with a nano SIM, while Samsung began using the smallest size in its Galaxy S6.

Before you purchase your new SIM, double-check the manufacturer's website to see what size you require. And if you're simply not sure, most networks now simply send out a triple SIM, so you'll get one of each size.

How do I keep my old number?

Ever heard of PAC codes and wondered what a classic 80s arcade game had to do with telephone numbers? It actually stands for Porting Authorisation Code, and it's the set of digits that you need to grab from your old network to let you transfer over your existing mobile number. If you're on one of the major networks, you can see what phone number you can contact them on here:

• EE 07953 966 250
• O2 0344 8090202
• Vodafone 03333 040 191
• Three 0333 300 3333

If you want to grab a bargain SIM only plan above, but it's on your existing network then your network won't release a PAC code and you'll be forced to take a new phone number.

At least you would have, if it wasn't for this clever (if convoluted) work-around. You have to order a free pay-as-you-go SIM from another network. Once you have it, you can tell your old network that you're moving and they'll give you that precious PAC code. Then, once your number is registered to the substitute network, simply get another PAC code from them. Take that to your old network, and they'll move your number to your new contract. Simple – kind of!

What contract length should I get?

Unlike with a contract, there's a lot more flexibility available when it comes to how long your SIM only plan will last. Two year commitments are virtually unheard of, with the norm being either one year or rolling one month contracts for ultimate flexibility. You can often get better prices if you tie yourself in for 12 months, especially on larger data tariffs. But sticking to one month at a time means that you can effectively hand pick a new plan to suit you every 30 days or so.

How much data do I need?

Because you can change your plan up more regularly than a normal, lengthier contract, it's less crucial to get this nailed from the start. But if you're thinking of grabbing a 12-monther or just put a personal pride on getting things right first time, then we'll help you pick out the sweet spot of data for you.

Firstly, check your phone to see how much data you've been using to date, and whether you have the tendency to use more than your current allowance every month. Then, if you're still unsure, check out our guidance: 

• 0-1GB Tiny amounts of data on SIM only deals could be a blessing or a curse. If you're putting it in a rarely used phone that will scarcely be away from wi-fi then you're quids in. But if you end up with one because your head's turned by the incredible price, then you could end up paying more if you continually go over your allowance.
• 2-3GB For anybody who needs data for little more than the occasional Google Maps route planning, 2GB and 3GB plans come cheap and give you much more freedom to check the football scores and scroll Facebook away from the wi-fi without danger.
• 4-8GB If you can't leave the house without having a music streaming service like Spotify pouring into your ears, then it might be worth paying for some extra GBs of data.
• 10-16GB This is a significant amount of data and some networks offer it for a very appetising price. Whether streaming music, downloading podcasts, watching social media videos, or all three is your thing – you should be covered.
• 20-30GB Only smartphone junkies that need regular (and hefty) data fixes need bother with this avalanche of GBs. You'll be able to rinse Netflix, Spotify and online games without too much fear of topping out.
• Unlimited Maybe it's because you use remarkable amounts of data. Maybe it's because you simply don't want to keep checking how much data you've used every month. Whatever your reason to go unlimited, you have only two choices when it comes to network: Three or GiffGaff.

Do I need unlimited calls and texts?

Call it practicality, call it greediness, call it what you want – it's human nature to want 'unlimited' anything if offered. But you should think genuinely about whether you really need it in a world where the likes of WhatsApp and Skype let you call and text for free over wi-fi or 4G. If you decide that a few thousand monthly minutes and texts should do you, then you could shave off some cash from your bill.

What's the best mobile network for SIM only?

While EE, O2, Vodafone and Three are generally considered the major four networks for contract plans, when it comes to SIM only there are some other key players are well worth a look. See what we think of them below, and whether you'll get any free perks to help persuade you to sign up. Plus, we'll tell you about a couple of other SIM sellers that might be able to wrangle you an even better deal.

EE SIM only deals

If you want fast and furious 4G, then your choice has to be EE. Its speeds are around 50% faster than the other major networks, which is really noticeable if you like watching films or football on the move. Talking of sport, EE gives you three free months of BT Sport when you sign up, as well as six months of Apple Music.

View all: EE SIM only deals 

O2 SIM only deals

O2's best claim for your contract is with its Priority rewards – from cheap weekly lunch deals and pre-order privileges on gig tickets, to ad-hoc discounts and competitions. Plus, they have 100s of wifi hotspots in shops and cafes that you can connect to for free and save your precious data.

View all O2 SIM only deals 

Vodafone SIM only deals

Vodafone seems to have been around since mobile phones were cumbersome bricks, but they remain a major player. Take a mobile contract and they'll throw in your choice of a NOW TV Entertainment Pass, Spotify Premium or Sky Sports Mobile subscription. And your plan will be available to use in more than 100 countries.

View all Vodafone SIM only deals 

Three SIM only deals

Three is still the only network to offer unlimited data and it often features unbeatable deals on other big data plans – that makes them a natural choice of many a data hungry smartphone addict. But it's a bit shy on the free promotions stuff, and 4G coverage isn't as strong as the other networks.

View all 3 mobile SIM only deals 

BT SIM only deals

That familiar old stalwart of telecommunications BT is so-so when it comes to SIM only tariff prices. That's unless you're already a BT broadband customer, in which case you get some really favourable prices – a fiver less than the rest of the hoi polloi. Plus you get to choose an Amazon or iTunes voucher, the value of which depends on how much data you're in for.

Check below to see the current prices plans and how what voucher you can claim when you sign up.

For existing BT Broadband customers
(click the customer option at the top if the prices are more expensive)

12 months | 500MB data | 400 minutes | Unlimited texts | £20 Amazon or iTunes gift card – £5 per month at BT

12 months | 3GB data | 1000 minutes |Unlimited texts | £40 Amazon or iTunes gift card – £8 per month at BT

12 months | 6GB data | Unlimited calls and texts | £70 Amazon or iTunes gift card – £12 per month at BT

12 months | 15GB data | Unlimited calls and texts | £90 Amazon or iTunes gift card – £16 per month at BT

For non-BT Broadband customers:

12 months | 500MB data | 400 minutes | Unlimited texts | £20 Amazon or iTunes gift card – £10 per month at BT

12 months | 3GB data | 1000 minutes |Unlimited texts | £40 Amazon or iTunes gift card – £13 per month at BT

12 months | 6GB data | Unlimited calls and texts | £70 Amazon or iTunes gift card – £17 per month at BT

12 months | 15GB data | Unlimited calls and texts | £90 Amazon or iTunes gift card – £21 per month at BT

iD SIM only deals

iD is a good option if bargain basement prices are what you covet most. This is a network run and owned by Carphone Warehouse – it piggybacks on the Three network. It's an excellent option if you want great value on a rolling monthly contract.

View all iD SIM only deals

giffgaff SIM only deals

GiffGaff is very hard to beat on price – if you want to grab a cheap SIM card deal, this could be your best option. You can't argue with £5 a month. The cheap deals don't give you much of an allowance to play with, but if you just want to keep your phone going and available to use for calls and texts with the occasional bit of internet use outside of your home WiFi, GiffGaff is a strong offering. Look out for the T&Cs though as some of the big data deals throttle the speed after a few gig.

View all giffgaff SIM only deals

Virgin Mobile SIM only deals

Virgin Mobile has been going for a long time, and some of its SIM only deals are particularly attractive. They're all one-month rolling contracts, so you can stop paying at any time if you so wish, giving you flexibility if you want to change your plan or go for a phone-inclusive deal down the line. Prices start from as little as £6 a month.

View all Virgin Mobile SIM only deals

Tesco Mobile SIM only deals

The UK's biggest supermarket has been known to offer competetive – if not stellar – SIM only deals, with low data prices starting around the £6 a month mark. Where it get's really interesting is if you download the Xtras app to an Android phone: you'll save £3 on your monthly bill, but you will have to see adverts every time you unlock your handset.

View all Tesco Mobile SIM only deals

TalkTalk SIM only deals

TalkTalk is a telecoms company that also offers home phone, broadband and TV packages, so the best deals can be had if you sign up for more than one service. However, at the time of writing the cheapest deal is £3.95 per month for an admittedly measly 250MB of data. Better yet, for just £7.75 you can get 2.1GB.

View all TalkTalk SIM only deals

Plusnet SIM only deals

Plusnet might be more well known for its broadband deals, but it's also keen to push some very cheap 30-day SIM only deals. You don't have to be a Plusnet customer, although you could get double the data on some of these SIM only deals if you are. You don't have to worry about signal either as Plusnet uses EE's network that covers 99% of the UK. Plusnet's latest cheap SIM only deals start at just £5 a month, check them out via the link below.

View all Plusnet SIM only deals

Freedom Pop SIM only deals

Freedom Pop is trying something new – offering contracts for FREE. The catch being that you only pay if you do over the allowances of your bundle or opt for a larger deal. The prices for doing so vary, so be sure to take a look at the small print. It seems that they feature a different offer each week, but seeing as you can cancel at any time, they may be worth a look.

View all Freedom Pop SIM only deals

Mobiles.co.uk SIM only deals

It's always worth checking out Mobiles.co.uk before settling on your SIM – its aggressive price cuts are often unmatched by anyone else. While the online retailer is known more for its handset contracts, it also offers a wide range of SIM only deals from all your favourite networks.

View: SIM only deals at Mobiles.co.uk

Carphone Warehouse SIM only deals

Carphone Warehouse doesn't just sell handset contracts. It also has a wide range of SIM only deals for Vodafone, O2, EE and ID. The online store is also known to include additional incentives such as half price fees for six months, free Beats by Dre headphones or Currys vouchers.

View all Carphone Warehouse SIM only deals

Which networks have coverage in my area?

It's one of life's (many) little frustrations – you sign up with a network, get your SIM up and running and then discover that you get no coverage at all in your house. Well this little pain in the neck can be avoided by using the dedicated coverage checker that most networks provide. Enter your postcode and you'll see whether your address has 2G (calls, texts and email), 3G (the basics plus picture messaging and faster web browsing) and 4G (all the powers of 3G, plus faster downloads, online gaming and media streaming) coverage.

We've provided links below to all the available coverage checkers on multiple networks. We'd advise not only checking coverage in your home, but also work, school, uni, favourite pubs and so on. Anywhere where you spend time on a regular basis really.

• EE coverage checker
• O2 coverage checker
• Vodafone coverage checker
• 3 mobile coverage checker
• BT mobile coverage checker
• iD coverage checker
• GiffGaff coverage checker
• Virgin mobile coverage checker
• Tesco mobile coverage checker
• TalkTalk coverage checker
• Plusnet coverage checker
• Freedom Pop coverage checker

How does TechRadar make money from SIM only deals?

If you buy a phone after visiting this page, TechRadar will be paid a small commission by the network or reseller you buy from. This money is paid by the site you buy from and thus does not affect the amount you pay for your phone contract. If you go direct to the site you buy from, you would pay the same amount.

While some sites out there will be paid larger fees for pushing people to specific deals that aren't necessarily the cheapest, TechRadar will always find you the absolute best value. Trust and integrity is important to us, so if you ever think we're not displaying the very best deals let us know.  

The SIM only deals on this page are checked every day to make sure they're still available and up to date! If you're ready to go SIM only, then head back to the top of this page and use our tool to find the perfect plan…

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