You can often save hundreds of pounds per year by getting a low-cost SIM card for your mobile phone. We compare the UK’s best value smartphone SIM-only deals.

A great way to save money on your mobile phone bill is to change your tariff to a SIM-only deal. Compared to a normal mobile contract, you can usually save hundreds of pounds per year whilst keeping the same phone number as before. You’ll also get lots of flexibility with the choice of either a 1-month or 12-month contract.

In this article, we’ll review and compare the UK’s best value smartphone SIM-only deals. We’ll compare SIM-only deals from 14 different mobile networks: from the big names like EE and O2, to lower-cost virtual network operators like giffgaff, iD Mobile, Plusnet and Smarty.

SIM Only Deals: How Do They Work?

A SIM-only deal for your mobile phone gives you an monthly allowance of minutes, texts and mobile data. As SIM-only deals aren’t bundled with a handset, it’ll normally be cheaper and much more flexible switching to SIM-only.

Typically, most people will be able to savshowe more than £100 per year switching from a normal mobile contract to a SIM-only deal. You’ll need to provide an unlocked smartphone to make the switch to SIM-only, and you’ll be able to keep your existing phone number with a PAC Code.

Here are three key things you should know when choosing a SIM-only deal:

1. You’ll always get coverage from EE, O2, Three or Vodafone.

  • EE
  • O2
  • Three
  • Vodafone

The UK has only four coverage providers: all other mobile networks will piggyback on one of the four.

When it comes to SIM-only deals, there are currently 14 mobile networks you’re able to choose from. While this appears to be fairly complicated at first glance, it’s worth being aware there are actually only four network coverage providers underlying all of the services.

Besides the four major networks (EE, O2, Three and Vodafone), you’ll find a number of “virtual network operators” piggybacking on coverage from one of the main providers:

When using a virtual network operator, you’ll have access to the same signal as if you were using the underlying provider directly. To find out more and to compare the coverage in your area, please see our list of UK mobile phone coverage checker tools.

2. You can keep your current mobile number.

It’s a straightforward process to keep your current phone number when moving to a SIM-only deal.

If you’re changing mobile networks, you’ll need to obtain a PAC Code from your old mobile network. The process of transferring your phone number takes about one working day: our PAC Code Finder can walk you through the process one step at a time.

3. You might need to unlock your smartphone.

If your smartphone was originally provided by another mobile network, it might be necessary for you to unlock it before you can use it on another network.

For more information about unlocking your handset, see our in-depth guides to unlocking an iPhone and unlocking a Samsung Galaxy smartphone.

Recommended Deals

The most suitable SIM-only deal depends on your requirements: there isn’t a universal “best SIM-only deal” for everyone. In this section, we’ll outline some of our recommended SIM-only deals with a number of key features.

For Flexibility & No Credit Check

If you want ultimate flexibility, without the need to undergo a credit check, our recommendation is to order a free SIM card from giffgaff.

On giffgaff, you can get unlimited minutes, unlimited texts and 3GB of 4G internet for £10/month. This is increased automatically to 4GB per month once you’ve been on the tariff for 3 months. On giffgaff, there’s no need to sign any contracts so you can join or leave at any time. giffgaff also works on a pre-paid basis so there’s no need to undergo a credit check for the service.

£8 Goodybag500Unlimited2GB£8.00
£10 GoodybagUnlimitedUnlimited3GB£10.00
£12 GoodybagUnlimitedUnlimited4GB£12.00
£15 GoodybagUnlimitedUnlimited8GB£15.00
£20 GoodybagUnlimitedUnlimited20GB£20.00
£25 GoodybagUnlimitedUnlimitedAlways-On£25.00

giffgaff is a low-cost sub-brand of O2 offering the same 2G, 3G and 4G coverage available to customers on O2. For more information, please see our in-depth review of giffgaff.

For Families & Spend Control

For families wanting a single combined bill for everybody’s usage, BT Mobile is our recommended network (specifically, their Family SIM offer).

With Family SIM, households can have up to five SIM cards on one combined bill. Each SIM card has its own individual allowance along with a built-in spend cap to prevent unexpected out-of-allowance charges. Customers will get an online dashboard for managing their family’s spending, and will have the ability to delegate control on a SIM card-by-SIM card basis. There are also discounts available when multiple family members join BT Mobile, with the size of the discount rapidly increasing as more family members join.

The following table shows the cost of your first BT Mobile SIM card, assuming you’re currently a BT Broadband customer. Additional Family SIM cards will come with a further discount on this price.

BT MobileUnlimitedUnlimited2GB£10.00
inc. £5 discount
BT MobileUnlimitedUnlimited8GB£12.00
inc. £5 discount
BT MobileUnlimitedUnlimited3GB£12.00
inc. £5 discount
BT MobileUnlimitedUnlimited6GB£13.00
inc. £5 discount
BT MobileUnlimitedUnlimited8GB£14.00
inc. £5 discount
BT MobileUnlimitedUnlimited12GB£15.00
inc. £5 discount
BT MobileUnlimitedUnlimited15GB£18.00
inc. £5 discount
BT MobileUnlimitedUnlimited20GB£25.00
inc. £5 discount
BT MobileUnlimitedUnlimited40GB£30.00
inc. £5 discount

For more information, please see our review of BT Mobile and the BT Family SIM offer.

For Tethering & Personal Hotspot

If you’d like to get your laptop or tablet connected on-the-go, it’s worth being aware that only certain mobile networks will allow you to tether and to share your data via a hotspot.

Some lower-cost mobile networks like iD Mobile and Virgin Mobile prohibit the use of tethering on their network. Sometimes, certain plans are also excluded from tethering on some networks e.g. Three doesn’t allow you to tether on lower-cost Essential price plans.

The following table shows some of our recommended SIM-only deals for customers who want to be able to tether:

Tesco Mobile1,0005,0005GB£11.00

For more information, see our in-depth guide to tethering on UK mobile networks.

For Fastest Download Speeds

If you want access to the fastest 4G download speeds, EE is our recommended network for a new SIM-only deal. With EE, you’ll have access to double-speed 4G, and speeds of up to 60Mbps.


For more information, see our guide to double-speed 4G and EE’s tariffs.

For International Roaming

For customers wanting inclusive international roaming in 71 destinations (including Europe, the USA, Australia, Brazil, Singapore and more), Three offers Feel At Home Around The World on their ‘Advanced’ Pay Monthly SIM cards.

With Feel At Home, you can use your normal UK allowances at no extra cost when travelling abroad.


On Three’s lower-cost Essential plans, Feel At Home is only available when you’re travelling in Europe. For more information, see our full review of the Feel At Home offer or Three’s official webpage.

For Unlimited Data

  • giffgaff
  • Three

For customers wanting the peace of mind of unlimited data, there are currently suitable SIM-only deals available from giffgaff and Three.

giffgaff has the cheapest available SIM card with unlimited data: just £20/month will get you Always-On data (unlimited downloads with 4G speeds on the first 9GB per month). Three has a higher entry-level price for all-you-can-eat data, but has no limits on 4G usage (subject to TrafficSense policies).

Virgin MobileUnlimitedUnlimitedUnlimited£27.00

For more information, please see our in-depth guide to unlimited data tariffs.

Deals By Price Range

For a full overview of SIM-only deals by price range, please jump to the relevant section of this article:

Less than £10/month

5 Pound Note
In the UK, you can get a SIM-only deal for less than £5/month.

If you’re looking for a super-cheap SIM-only deal, the cheapest options currently available on the market start from around £5/month.

Typically, the best value SIM cards in this price range come from iD Mobile and Plusnet Mobile (both of them offer 1-month rolling contracts). For instance, iD Mobile offers 250 minutes, 5000 texts and 2.25GB of internet for £5/month.

iD Mobile uses 3G & 4G coverage from Three while Plusnet Mobile offers 2G, 3G & 4G coverage from EE. iD Mobile is the own-brand mobile network from the Carphone Warehouse and Plusnet Mobile is the low-cost sub-brand of BT.

The following tables show a full list of SIM-only deals available for under £10/month:

12 month contracts

Sky MobileUnlimitedUnlimited2GB£6.00
Virgin Mobile2,500Unlimited2GB£6.00
Virgin Mobile1,500Unlimited1GB£7.00
Tesco Mobile5005,0001GB£7.50
Tesco Mobile1,0005,0002GB£9.00

1 month contracts

iD Mobile500Unlimited500MB£3.99
iD Mobile150Unlimited500MB£3.99
iD Mobile500Unlimited1GB£5.00
ASDA Mobile1252,000250MB£5.00
Plusnet Mobile250500500MB£6.00
ASDA Mobile300Unlimited1GB£7.00
Tesco Mobile2505,000250MB£7.50
iD Mobile1,500Unlimited3GB£8.00
Plusnet Mobile1,000Unlimited1GB£8.00

From £10/month

The vast majority of SIM only deals start from £10/month.

At the £10/month price point, there’s a huge variety of SIM-only deals.

On a 1-month contract, some of the best value deals are available from giffgaff, iD Mobile and Smarty. Our recommended deal is giffgaff’s £10 goodybag which gives you unlimited minutes, unlimited texts and 3GB of data (plus an extra 1GB of free data once you’ve been a customer for 3 months). giffgaff uses coverage from O2, whereas iD Mobile and Smarty use coverage from Three.

On a 12-month contract, the best value deals currently have a similar amount of data as on the 30-day contracts. However, you may be able to get additional benefits when choosing a 12-month plan. For instance, Three has an “Advanced” SIM-only deal with inclusive roaming in 71 destinations. Meanwhile, Vodafone offers a Basic SIM Only deal with unlimited calls, but usage is limited to inside the UK only.

12 month contracts

Virgin Mobile5,000Unlimited10GB£10.00
Tesco Mobile1,0005,0005GB£11.00
Sky MobileUnlimitedUnlimited4GB£12.00
BT MobileUnlimitedUnlimited500MB£13.00
Tesco Mobile5,0005,00010GB£14.00

1 month contracts

iD Mobile500Unlimited5GB£10.00
Lebara MobileUnlimitedUnlimited4GB£10.00
ASDA Mobile600Unlimited3GB£10.00
Plusnet Mobile1,500Unlimited2GB£10.00
Tesco Mobile5005,0001GB£10.00
ASDA Mobile800Unlimited4GB£12.00
iD Mobile1,000Unlimited6GB£12.50
Plusnet Mobile2,000Unlimited3GB£12.50

From £15/month

15 Pound NotesThere are a wide variety of SIM-only deals to choose from at the £15/month price point. You can get a data allowance of up to 8GB per month, along with unlimited calling & unlimited texts on many mobile networks.

One of the best deals at this price range is Smarty’s £15 Large tariff. You’ll get 8GB of data along with unlimited calls and unlimited texts, plus a discount every month for your unused data.

The following SIM-only deals are currently available from £15/month:

12 month contracts

Sky MobileUnlimitedUnlimited8GB£15.00
BT MobileUnlimitedUnlimited2GB£15.00
BT MobileUnlimitedUnlimited8GB£17.00
BT MobileUnlimitedUnlimited3GB£17.00
Tesco Mobile5,0005,00020GB£18.00
BT MobileUnlimitedUnlimited6GB£18.00
BT MobileUnlimitedUnlimited8GB£19.00

1 month contracts

iD MobileUnlimitedUnlimited8GB£15.00
Lebara MobileUnlimitedUnlimited6GB£15.00
ASDA Mobile1,000Unlimited6GB£15.00
Plusnet MobileUnlimitedUnlimited4GB£15.00
Tesco Mobile5,0005,0004GB£15.00

From £20/month

20 Pound NoteAt the £20/month price point, most mobile networks are offering unlimited calls and unlimited texts. You can also get huge amounts of data at this price point (e.g. 30GB of high-speed 4G data from Three).

For unlimited downloads and greater flexibility, we’d recommend choosing giffgaff’s £20 goodybag. For £20/month, you’ll get unlimited minutes, unlimited texts and Always-On data. There’s no need to undergo a credit check for the service, and there are also no contracts to sign.

The following deals are also available from £20/month:

12 month contracts

Virgin Mobile5,000Unlimited50GB£20.00
BT MobileUnlimitedUnlimited12GB£20.00
BT MobileUnlimitedUnlimited15GB£23.00

1 month contracts

iD MobileUnlimitedUnlimited20GB£20.00
Lebara MobileUnlimitedUnlimited12GB£20.00
ASDA MobileUnlimitedUnlimited9GB£20.00

From £25/month

The following SIM-only deals are available for £25/month or more:

12 month contracts

Tesco Mobile5,0005,00050GB£25.00
Sky MobileUnlimitedUnlimited25GB£25.00
Virgin MobileUnlimitedUnlimitedUnlimited£27.00

1 month contracts

ASDA MobileUnlimitedUnlimited15GB£25.00

£30/month and more

The following SIM-only deals are available for £30/month or more:

12 month contracts

Tesco Mobile5,0005,00030GB£30.00
BT MobileUnlimitedUnlimited20GB£30.00
BT MobileUnlimitedUnlimited40GB£35.00

1 month contracts


More Information

For more information about the mobile networks listed in this article, please see our in-depth mobile network reviews. You may also find it helpful to read our guides on comparing mobile network coverage and how to transfer your phone number. If your smartphone was originally purchased from another network, you may also need to unlock it.

Prices change on an occasional basis. For this reason, you should always double-check the details on the mobile network’s website before signing up to any deal.

Your Comments 114 so far

We'd love to hear your thoughts and any questions you may have. So far, we've received 114 comments from readers. You can add your own comment here.

  • Hi,Ken,your website is excellent!It’s very helpful for me because it is difficult to understand the plans for mobile phones in the UK.

    I’m using 3’s Pay as you go currently.I think I want to move to monthly SIM-only deals. I’m interested in the following plans.
    I think Three is better if only the internet,and it’s not unnecessary to transfer. But If you think that there is any benefit in BT, please give me advice.

    Three(12-month contract)
    Unlimited Unlimited 8GB £10
    BT(12-month contract) I’m a BT Broadband customer.
    Unlimited Unlimited 4GB £10

    Many thanks.

      • Hi Ken,
        I really appreciate your message.I’m very sorry but I could not reply to you soon.
        I’ll decide to take Three’s plan.
        Many many thanks and have a nice spring time(It’s very cold today…..)!

  • The Phone Co-op used to offer Pay As You Use, which was a post-pay tariff with a £2 per month standing charge without calls, texts or data. Data bundles were available, so one can be a really low call/text user but get high value data. As it wasn’t pay as you go you didn’t have to make a call every 90 days or whatever to keep it active. Clearly there would be a moderately low break even point with bundles that might start at £5 or thereabouts (I see you list iD Mobile with some at £3.99), but it was unique for really low users who don’t want to have to be pay as you go.

    I am on the Phone Co-op Pay As You Use and have never been able to find another provider with similar offering. Ken, do you know of one?

    • Hi Dave,
      Thanks for your comment. I’m afraid I don’t know of any other such hybrid offering. Is there a reason something like 1pMobile, O2’s Classic Pay As You Go or Three’s 321 tariff wouldn’t work here? On those tariffs, there’s no monthly standing charge and the prices are as low as 1p/minute, 1p/text and 1p/MB (3p/minute, 2p/text and 1p/MB on the offerings from O2 and Three). On 1pMobile, you’ll need to top-up your phone by at least £10 every 120 days (automatic top-up functionality is available for this if you desire). Meanwhile, O2 and Three have no such minimum top-up requirement (you just need to use your phone for a chargeable activity at least once every 180 days).

      • Hi Ken,

        Thanks for replying to my comment.

        I hope this message isn’t too long – I do like to go into detail.

        I intend to continue on the Phone Co-op’s Pay As You Use service; I was just wondering whether there are any other similar post-pay plans out there. I have looked but been unable to find.

        I was on Orange’s OVP Virgin for about 10 years until they scrapped it in 2013. As off-net calls were 35ppm, moving to Phone Co-op’s PAYU brought me up-to-date in respect of not paying a premium to ring other networks.

        Phone Co-op PAYU allows me use of call divert. While 7ppm calls aren’t as cheap as the other services you mentioned, I like it because it has per-second billing and a minimum call charge of only 1.2p (1p plus VAT). Also, there is the ability to add a large data bundle if required, something which other post-pay plans would require subscription to a plan that includes many calls and texts I don’t use.

        I prefer the Phone Co-op’s PAYU. I appreciate that for such service the operator will have the expense of a credit check, something which isn’t required for PAYG. It would also take on risk of bills not being paid, all for little return. This may be the reasons that other operators aren’t interested in offering a similar service – pay as you go with low call rates sufficiently fills this part of the market.

        I dislike the idea of pay as you go as it means having to pay in advance for use of service at some unknown times in the future. Also, it is usually not possible to obtain an itinerary of what charges were spent on and call divert is generally not available (I know some smaller MVNOs allow it). While unlikely, there is always the risk that the account could be closed because circumstances meant it wasn’t used within the 90, 180 days or whatever (or worse, the operator decided to change the terms and I didn’t find out until it was too late).

        A few years ago I had a Vodafone “Top-Up and Go” 3G dongle where the only requirement was one use every 6 months. This was excellent as my use pattern was irregular/occasional. I came to connect short of six months since I last used it and it wouldn’t work. It turned out that Vodafone had moved the goal posts and scrapped the plan – only I didn’t know. Perhaps an SMS was sent to my account but I wouldn’t have seen it because I never accessed it. The “new” plans meant some amount of data would have to be used within 30 days (I seem to recall), whereas before there was no such restriction. Lesson learned not to trust them (and, of course, phone service comes with additional risk, however unlikely, of loosing the associated telephone number if the provider shuts the account, whereas with a data-only service the number is of no importance). This saga left a very sour taste.

        To return to the subject of Phone Co-op PAYU, I like my phone to be available to make calls should needs arise and that I am billed for only those items at the end of the billing period. I am happy to pay a moderate standing charge of a pound or two in order to maintain the account.

  • Martin Campbell said:

    Excellent and very informative site. Thank you. Question: If I buy a phone with a dual sim can I switch my number to both sim cards?

    • Hi Martin,
      Many thanks for your comment. With a PAC Code, you’ll be able to transfer your phone number onto one of the SIM cards. You can place that SIM card into your dual-SIM phone, but each of your two SIM cards will have a different phone number (as opposed to both SIM cards having the same number).
      Hope this helps,

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