If you stream songs or watch lots of video on the go, you’ll probably want unlimited data, or at least a generous allowance. Otherwise you could be looking at a nasty shock with your mobile phone bill. Here’s our guide to the best mobile data deals from all networks and handy tips on using mobile internet.
We've got all you need to know on mobile data plans from the different networks, so you can find what tariff is best for you - whether you're looking to use your mobile for watching videos online whilst out and about, or just want to ensure you can browse the web.
SIM only data plans
If you're after unlimited data but don't want a new handset, then a SIM only plan is for you. Below is a table of the main mobile networks' best data plans on SIM only.
Three is the standout network for unlimited SIM deals - its 'All-you-can-eat' data plans come with a variety of minutes and text allowances, as well as the option of monthly or annual plans.
On the other hand, some providers offer affordable plans with big data limits that should be more than enough for most. For example, Asda Mobile is currently giving free 12GB data to use before 1 January 2016 when you get a SIM-only plan (valid from 1 November to 1 January 2015).
Best SIM only data plans
|4GB data + 12GB FREE IN 2015||Unlimited data||4GB data||10GB data||20GB data||20GB data|
|3G included||4G included||4G included||4G included||4G included||4G included|
|1 month contract||12 month contract||12 month contract||12 month contract||12 month contract||12 month contract|
|£20.00 a month||£17.00 a month||£17.99 a month||£27.20 a month||£30.00 a month||£25.00 a month|
|Get deal||Get deal||Get deal||Get deal||Get deal||Get deal|
Mobile phones with unlimited data plans
Let's take a look at some smartphones that are popular for using large amounts of mobile data. After all, if you have the latest smartphone you're going to want to use it to its full potential without restrictions - exactly what an unlimited data plan is for.
12MP camera | Latest iOS | 3D Touch screen
|Monthly data allowance||Unlimited||20GB||3GB||4GB|
|See deal||See deal||See deal||See deal|
The newest iPhone is a stunner. Not only does it have the same stylish look as its predecessor, it's taken on a lot of upgrades on the inside too - there's a better operating system in the form of iOS 9, improved battery life, and a 12MP camera that can record video in 4K. You'll need a lot of data if you want to stream video on its HD screen or upload your 12MP photos to Facebook.
Unlimited data plans on the iPhone 6s are available on Three, though other networks offer some large data allowances as well.
iPhone 6s Plus
Large screen phablet | 12MP camera | Latest iOS
|Monthly data allowance||Unlimited||20GB||5GB||6GB|
|See deal||See deal||See deal||See deal|
iPhone 6s not big enough? Take a look at the 5.5-inch screen on the 6s Plus. It's got all the same specs as the 6s, only with extra screen real estate and a couple of additions to the camera - such as optical image stabilisation.
8MP camera with dual-LED flash | Large screen | Fast and easy to use
|Monthly data allowance||Unlimited||20GB||10GB||20GB|
|Get deal||Get deal||Get deal||Get deal|
The original iPhone 6 is available on plans with some pretty decent data as well - and higher allowances than the 6s, in some cases. With the iPhone 6, you'll get a nicely sized 4.7-inch screen, and slick software thanks to the Apple A8 chipset and iOS 8. The 8MP camera is impressive too, with dual-LED (dual tone) flash, autofocus, and large Focus Pixels.
Samsung Galaxy S6
Fast octa-core processor | Beautiful display | 16MP camera
|Monthly data allowance||Unlimited||20GB||10GB||6GB|
|See deal||See deal||See deal||See deal|
Samsung's latest flagship, the Galaxy S6, is a phone packed with a features, including a stunningly high-resolution display - perfect for streaming video and browsing Instagram. This is a phone that needs a lot of data to go along with it. Again, Three's the only network to offer unlimited data on the S6 right now, but you can get some pretty heavy allowances from other ones too.
Compare mobile data plans on networks
Each mobile network in the UK has its own approach to data. Some plans clearly state a set download allowance, while others described as 'unlimited' may still carry a fair usage policy.
The amount of data included in a monthly plan can vary depending on whether you're buying a phone and tariff plan together or just buying a SIM only deal.
A summary of the main UK mobile networks' largest data allowances for mobile phones, and their policies, can be found below.
|Fair usage policy||No ||Yes||Yes||Yes||Yes|
|4G included ||Yes||Yes||Yes||Yes||Yes|
|Use data abroad at no extra cost||Yes ||No||No||No||Yes |
|Monthly cost from ||£17.00||£25.99||£27.20||£30.00||£20.00|
|See more||See more||See more||See more||See more|
 Three doesn't have a fair usage policy in the UK (unless you use 1000GB which even heavy users wouldn't reach), but it does have one for abroad.  Subject to network coverage and you'll need a 4G phone.  You can use data abroad in 18 countries at no extra cost, up to 25GB per month. You can use your monthly allowance for not just data but also minutes and texts. Those countries are Australia, Austria, Denmark, Finland, France, Hong Kong, Indonesia, Israel, Italy, Macau, New Zealand, Norway, Republic of Ireland, Spain, Sri Lanka, Sweden, Switzerland and United States.  Three offers tethering of 2GB usage on unlimited plans with a handset and 4GB usage on SIM only unlimited data plans. Outside of that allowance you will be charged the regular rate per MB of usage for your plan. For other networks, tethering uses up your data allowance.  Prices correct for selected deal at the time of publishing.
Who is best for mobile data?
If you've got your heart set on an unlimited data plan then Three is the network for you. Not only do you get the peace of mind that you won't go over your limit, you can also use your data plan abroad in 18 countries - fantastic for keeping in touch with loved ones when you're on holiday and telling everyone how great a time you're having.
EE, Vodafone, and O2 all have fair usage policies, which means that they might restrict the amount of data you can consume if you're burning through megabytes at a rate of knots. Most customers probably won't feel any effect of a fair usage policy.
Specifically looking for a 4G data plan? You might want to consider EE. As the biggest and fastest network in the UK, you're likely to get better speeds and a more reliable internet connection with EE than any other - although Three isn't far behind EE on this.
When it comes to price, you don't need to look further than Three. At the moment, Three's unlimited data plans offer the best value for money in our eyes. If you want a second option, we'd say iD Mobile is a good shout, because it also offers very large data plans, running as a virtual network off the Three network infrastructure.
The best unlimited data deal if you already have a phone
£20.00 a month
30 day term
We recommend going for this 30 day plan with Three. You get 4G included at no extra cost and with the term being only 30 days, you can effectively test-drive the tariff and network to ensure it works for you. If you find that the coverage is great and you enjoy being on an unlimited data plan, then why not sign up to the 12 month plan, which will save you a few quid a month.
Data on networks
Mobile data is what Three prides itself on, especially with its All-you-can-eat mobile data plans. It provides 'genuinely unlimited' mobile internet use with no danger of bill shock, which you may get with other more restricted data plans.
Three doesn't separate 3G and 4G services. This means if you sign up to a Three All-you-can-eat data plan then you'll get 4G at no extra charge - so long as you're in an area covered by Three 4G and have a 4G-compatible phone, of course.
It also offers the best value for unlimited data - a standout winner with the cheapest prices and best range of plan features. It's the nearest to a truly unlimited data plan with 4G included, tethering up to 4GB, and the massive added bonus of being able to use your monthly allowance abroad in 18 countries.
Three unlimited All-you-can-eat plan
Compare the prices of getting an unlimited data plan with one of the latest handsets or as a SIM only deal.
|SIM only||iPhone 6s||Samsung Galaxy S6||iPhone 6|
|No upfront cost||£99.00 upfront||£19.99 upfront||No upfront cost|
|12 month term||24 month contract||24 month contract||24 month contract|
|From £17.00 a month||From £51.00 a month||From £48.00 a month||From £46.00 a month|
|Get deal||Get deal||Get deal||Get deal|
EE 4G plans come with varying data allowances, but none of them are unlimited. Plans range from 500MB to a massive 20GB of data a month. EE will let you know if you're close to hitting your limit, at which point you can always buy a data add-on to get more.
There's no other network that is bigger and faster than EE when it comes to mobile data. It has more customers than any other network, and is the award winner for the RootMetrics overall UK network performance.
You can also share a plan on EE, which could save your family members forking out for their own individual plans. 4GEE Plans can be shared with up to four other people within your household and everyone gets unlimited call and texts - it's just the data allowance that gets shared.
£17.99 a month
12 month term
BT Mobile - the owner of EE's network - doesn't offer any unlimited data plans, but it does have 4G. If you're concerned about your usage, BT also let you set a monthly spending cap to ensure you don't overspend on your phone bills - and it stays in place even if you go abroad.
Already a BT broadband customer? Good news - BT will give you a discount on its SIM only plans.
£20.00 a month
or £25.00 a month for non-BT broadband customers
12 month term
If you pick a Vodafone 4G plan, a set data allowance - anywhere between 250MB and 20GB - will be stated in the contract. You can then check what you're using via the MyAccount page on Vodafone's website.
Vodafone has partnerships with Spotify, Now TV and Sky Sports to bring entertainment packages to some of its Red plans. This means that you could get access to some of the latest movies, live sport and music through your Vodafone plan.
£24.30 a month
12 month term
4G plans from O2 aren't offered with unlimited data, though data allowances on its phone plans are pretty generous. There's not much chance of you accidentally going over your data limit either - O2 lets you know if you're getting close to it, and you can always purchase top ups.
It may not be the best value if you're looking for a big data allowance, but there are other benefits. O2 Priority, for instance, gives you exclusive offers such as VIP tickets to the latest gigs, discounts on high street retailers, and prize draws to win a whole range of treats.
£23.80 a month
1 month term
iD Mobile from Carphone Warehouse
The network brought to you by Carphone Warehouse, iD Mobile, offers customers very large data tariffs. iD uses the Three network for its coverage, and offers add-ons so you can tailor your plan to suit your needs - add minutes, texts, or data to your allowance when you need them.
giffgaff does things a little differently from most networks. It's online-only, its community provides technical support, and its phones are paid for through peer-to-peer lending - so the more you pay upfront, the less you pay each month. With giffgaff you pick a 'goodybag' of calls, texts and data, one of which includes 3G with unlimited data. Unfortunately, however, it doesn't offer plans with 4G.
Goodybags are pay-monthly, but there's no minimum contract term - if you find you don't actually need that much data you can switch to a cheaper limited data plan the next month.
Virgin Mobile offers a 3G data on Freestyle tariffs, which let you change the amount of call minutes, texts, and data you pay for each month, depending on what you need. It's flexible, but still rewards commitment - the longer you have the plan, the cheaper it gets. You'll also pay less for a plan if you're an existing Virgin Media customer for their TV and broadband packages.
One thing to note, however, is that Virgin Mobile does not offer any kind of 4G service yet.
Much like Three, if you have a 4G-compatible phone, Tesco Mobile gives you 4G at no extra cost. Unfortunately, none of its 4G plans are unlimited. The maximum data allowance available is 8GB a month - generous enough to do a fair bit, and you'll be warned if you're nearing your limit.
Mobile by Sainsbury's
Mobile by Sainsbury's is all about affordable SIM only plans and good value 30-day call, text and data bundles. While none offer unlimited data, or even 4G, their plans are still worth looking at if you want a couple of GB of data each month without spending too much.
The People's Operator
The People's Operator, or TPO, does pay-monthly and pay-as-you-go SIM only plans with some of what you spend on them going to a charity of your choice. It doesn't offer 3G plans with unlimited data or any 4G plans at all, and its top-end plans give you 3GB of data a month.
However, it has previously offered 3G with unlimited data as a special deal, so if the idea of a more socially-conscious network appeals, check to see if any such deals are currently running.
TalkTalk Mobile has unlimited 3G data plans available - but all TalkTalk plans are only available to existing TalkTalk customers. As an MVNO (mobile virtual network operator), TalkTalk Mobile uses the Vodafone network for its mobile services so it covers 99% of the UK.
Do I need unlimited data?
That depends. Getting an unlimited data package gives you peace of mind that you'll never go over your monthly data allowance. You won't have to worry about how much data you consume, you won't receive hefty charges on your monthly bill, and your network won't cut your internet connection off when you're busy browsing the web or halfway through an episode of Breaking Bad.
You might, however, pay a premium price for the luxury of having an unlimited data plan that you don't really need.
The average customer uses less than 1GB data per month. But the amount of data you need really depends on how much you use your phone for emailing, watching videos, downloading apps, streaming music, using Facebook and Twitter, and browsing the internet.
It boils down to this: do you plan to use the web extensively when out and about? Will you watch films and TV shows and stream music from apps when you're not connected to Wi-Fi? If so, you'd definitely benefit from unlimited data. If not, you'll probably be fine with a data limit.
What does 1GB of data mean?
So what can you actually do with 1GB of mobile data? We've put together a simple table of what 1GB translates to when using your mobile phone on a day to day basis.
|BBC iPlayer||Watching TV episodes in standard definition||2 hours|
|Netflix||Watching TV or films in HD (high definition)||1 hour|
|Call of Duty, FIFA||Playing games online||40 minutes|
|Facebook, Instagram||Posting photos on social media||500 photos|
|Skype, Facetime||Video calls||3-5 hours|
|iTunes, Spotify||Downloading music||150 songs|
|Sending and receiving basic emails||10,000 emails|
|News (Guardian, BBC, etc.)||Browsing web pages||40 hours|
|Sending messages via apps||1 million|
What is a fair usage policy?
Does 'unlimited' really mean you can munch as many megabytes as you like?
The main mobile networks in the UK - Three, Vodafone, O2, and EE - have their own approaches to data. Some plans clearly state a set download allowance, while others described as 'unlimited' may still carry a fair usage policy.
When choosing a mobile network, it's a good idea to look at the terms and conditions, as some deals will suit your needs better than others.
While mobile phones plans are often labelled as offering 'unlimited' data by networks, the amount of data you can actually use is usually capped by a fair usage policy - a set of guidelines laid out in the terms and conditions. Breach the fair usage policy, and your mobile phone bill could increase significantly, as additional charges may apply if you've used too much data.
To stay out of the danger zone, make sure you understand your network's fair usage policy. If you think you might breach it, take a look at these…
4 ways to cut down on your data usage
1. Hook up to Wi-Fi hotspots
Data usage depends on how often you connect to Wi-Fi. Hooking up to the Wi-Fi at home, in the office or at thousands of free Wi-Fi hotspots across the country means you won't be eating into your data allowance while you're connected.
2. Turn off video autoplay
Sites like Facebook and Twitter now have an autoplay function, which means that your phone may automatically start streaming the videos in your newsfeed.
If you don't want to eat up so much data watching the latest viral videos, disable the autoplay by setting it to Wi-Fi only (or switching it off entirely). You'll find this in the Settings section of the app.
3. Download movies and TV episodes before you leave the house
Downloading a TV episode on BBC iPlayer before you leave home for the day could save you a good chunk of your mobile data allowance.
If you watch around two hours of standard definition programmes a week on your mobile device, then you could save roughly 4GB of data a month by downloading on Wi-Fi instead of streaming.
4. Downsize your photo sharing
Sending smaller resolution versions of your pictures, whether via email or uploading to Twitter or Facebook, can significantly reduce the amount of data you're using. Does that selfie really need to be in super high resolution?
What is mobile data?
In the same way that mobile networks charge you to make calls - or include a certain number of minutes with a pay-monthly plan - there are costs involved with connecting to the internet on your phone.
To help keep traffic flowing and make sure they're not overloaded, networks charge you for using mobile internet. Instead of paying by the minute as you do with calls, you're billed according to how much data you use.
The latest generation of mobile broadband is 4G, which is much faster and more reliable than 3G, though some networks have begun trialling 5G too.
For more, take a look at our guide to mobile data.