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 gives you more flexibility (especially if you go for a 30-day rolling contract) or is ideal if you're eyeing up a new SIM-free phone.
So if you've come to the end of your phone contract, you don't necessarily have to speak to your network for an upgrade or start your hunt for a new mobile phone deal. Instead, you can go SIMO (to give in to the common parlance) and use our handy SIM only deal comparison chart above.
The good news is that SIM only deals are a cheap way of running your phone, with the cheapest deals starting at way less than a fiver a month. And even though its prices have recently gone up, Three remains king of SIMO thanks to its great value tariffs across multiple data allowance points. Although the last few weeks have seen Carphone Warehouse-owned retailer Mobiles.co.uk come up with some very tempting cashback opportunities with its SIM card plans -up to £84 in some cases.
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.
Top 10 best SIM only deals of the week are:
We've run the figures and plucked out the very best sim only deals available this month. 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 | 1 month contract | 500MB data | 150 minutes | Unlimited texts | £3.99 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 the least you can pay. You'd be advised to either keep mobile data switched off or be careful what apps are updating in the background. Or just pay a little extra for more data....
View this SIM only deal at iD/Carphone Warehouse
2. and 3. The best 1GB SIM only deals
iD Mobile | 1 month contract | 1GB data | 500 minutes | Unlimited texts | £5 per month
iD's fiver SIMO deals are often among our favourites, and this is no different. We're a little disappointed that its promotional 2.25GB tariff at the same price has now been removed, but this SIM plan remains one of the most impressive around at the moment. A few quid more gets you way more data though, so you keep scrolling down if you're worried that 1GB won't quite be enough for your web surfing, WhatsApping, Google Mapping needs.
View this SIM only deal at iD/Carphone Warehouse
O2 | 12-month contract | 1GB data | 500 minutes | Unlimited texts | £8 per month (after cashback)
OK, so it's not as cheap as the fiver iD tariff. But if you want to go for a network that's a little bit more recognisable and has those juicy Priority rewards, then this new O2 SIMO deal may sit better. It's all the same allowances, but you do have to sing a little for your supper. The reason it works out to £8 a month is due to £84 cashback that you have to claim in five instalments over the year contract.
View this O2 SIM only deal from Mobiles.co.uk
4. The best 2GB+ SIM only deal
iD Mobile | 1 month contract | 4GB data | 500 mins | Unlimited texts | £8 per month
iD is DOMINATING the low cost SIMO game at the moment, and this promotional tariff has to be the best value of them all. If you're prone to viewing a few YouTube videos and streaming some Spotify songs away from Wi-Fi, then a 4GB option may suit you better than the lower data SIMs above. £8 a month for this amount of data really is excellent, considering you don't have to faff around with any cashback or voucher codes.
Get this great value 4GB SIM from iD Mobile
5. The best 10GB+ SIM only deal
Three | 12-month contract | 12GB data | Unlimited calls and texts | £16 per month
This Three tariff remains one of the most popular on the market. £16 for a very healthy 12GB of data is superb value for your new unlocked handset or beloved old mobile. Plus, this deal hits the sweet spot between plenty of data for surfing and streaming, and extremely reasonable monthly bills. One of our go-to SIMO deals from the ever-trusty Three network.
View this fantastic Three SIM only deal direct from the network
6. The best SIM only deal for unlimited data
Giffgaff | No contract | All-you-can-eat data | Unlimited calls and texts | £20 per month
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. A quick word of warning... once you've used 9GB of data each month, Giffgaff will cut your speed down from 4G. But the next best unlimited data deal from Three has just shot up wildly in price.
Get this unlimited data deal on Giffgaff
7. Best EE SIM only deal
12-month contract| 10GB data | Unlimited calls and texts | £20 per month
If we're going to call a spade a spade, EE SIM only deals aren't cheap. In fact, they're usually more expensive than the likes of Three and Vodafone. But we know that people crave the network's rapid 4G speeds, so we feel it's our duty (dammit) to tell you the best value EE SIM only deal. 10GB is a generous data allowance and £20 per month probably won't break the bank - especially now that Mobiles.co.uk is giving £30 cashback. But if it's the best value you need, then do consider other networks first.
Get this EE SIM only deal from Mobiles.co.uk
8. Best Three SIM only deal
12-month contract | 30GB data | 600 mins | Unlimited texts | £19 per month
Three is often the go-to network for big data deals and its exceptional 30GB data deal won the Deal of the Year award at the Mobile Choice Consumer Awards 2017 thanks to the sheer amount of data for less than £20 a month. The only fiesy in the ointment are that this used to be even cheaper and the 600 minute cap on calls has just been re-introduced.
View this 30GB 3 Mobile SIM only deal
9. Best Vodafone SIM only deal
12-month contract | 8GB data | Unlimited calls and texts | £11 per month (after cashback)
Carphone Warehouse-owned Mobiles.co.uk is throwing a lot of cashback around at the moment to get you to grab a SIM from them. £84 cashback brings this deal down to an effective £11 per month, which is excellent value for this amount of data on one of the four major networks. Well worth a sniff, this from a network that often struggles to be competitive on SIMO.
View this big cashback 8GB Vodafone SIMO from Mobiles.co.uk
10. Best data only SIM deal
Three | 12-month contract | 10GB data | £8 per month
If you use your tablet as a kind of portable TV for catching up with Netflix, iPlayer and Amazon Video while out and about, then this Three data only deal just got even better. You now get 10GB for a mere £8 a month, which is cheaper than other major networks. This is by far the best value we can find for using data on an iPad or other tablet.
View this data only SIM deal from Three
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:
- 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.
- 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 can be. Teaming a SIM only plan with a standalone SIM-free handset could save you a few quid. It's usually the case when a flagship phone hits the market and contracts are made deliberately expensive. Take the Samsung Galaxy S8 as a prime example, where you could have saved over £100 over two years by splashing the £800-odd for the handset and slipping in a cheap SIM card.
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.
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 an iPhone X, 8, 8 Plus, 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 (8.8x12.3mm) 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
- ID 0333 003 7777
- GiffGaff 43431 from your handset
- Virgin 0345 6000 789
- BT 0800 800 150
- Tesco 0345 301 4455
- Sky 03300 412 524
- Asda 0800 079 2732
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 an EE SIM only deal. 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. And EE gives you three free months of BT Sport, 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 lunch deals and pre-order privileges on gig tickets, to ad-hoc discounts and competitions. Plus, they have 1000s of Wi-Fi 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. Look out for a Red Entertainment tariff, which gives you your choice of a NOW TV Entertainment Pass, Spotify Premium or Sky Sports Mobile subscription.
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. And it has has just started getting generous with perks - you can get cheap dinners and free coffees through its Wuntu app.
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 usually get a BT Reward Card with the majority of plans that can be spent anywhere that accepts Mastercard, the value of which depends on how much data you're in for.
Check below to see the current prices plans and what value Reward Card 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 | Unlimited calls and texts | £10 BT Reward Card - £8 per month at BT
12 months | 5GB data | Unlimited calls and texts | £25 BT Reward Card - £12 per month at BT
12 months | 6GB data | Unlimited calls and texts | £40 BT Reward Card - £17 per month at BT
12 months | 10GB data | Unlimited calls and texts | £40 BT Reward Card - £17 per month at BT
12 months | 20GB data | Unlimited calls and texts | £55 BT Reward Card - £20 per month at BT
12 months | 25GB data | Unlimited calls and texts | £55 BT Reward Card - £27 per month at BT
12 months | 40GB data | Unlimited calls and texts | £55 BT Reward Card - £35 per month at BT
For non-BT Broadband customers:
12 months | 500MB data | Unlimited calls and texts | £10 BT Reward Card - £13 per month at BT
12 months | 5GB data | Unlimited calls and texts | £25 BT Reward Card - £17 per month at BT
12 months | 6GB data | Unlimited calls and texts | £40 BT Reward Card - £22 per month at BT
12 months | 10GB data | Unlimited calls and texts | £40 BT Reward Card - £22 per month at BT
12 months | 20GB data | Unlimited calls and texts | £55 BT Reward Card - £25 per month at BT
12 months | 25GB data | Unlimited calls and texts | £55 BT Reward Card - £32per month at BT
12 months | 40GB data | Unlimited calls and texts | £55 BT Reward Card - £40 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 regularly offers some of the cheapest SIMO deals out there. They don't give you much of a data 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 Wi-Fi, 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.
View all Virgin Mobile SIM only deals
Tesco Mobile SIM only deals
The UK's biggest supermarket has been known to offer competitive - if not stellar - SIM only deals, with low data prices starting at not much more than a fiver a month. 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
Plusnet SIM only deals
Plusnet might be more well known for its broadband deals these days. but it's also keen to push some very cheap 30-day SIM only deals. 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 around £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.
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 - so check out what's available right now.
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
- 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...