Mobile broadband usage guide: what can you get for your gigabyte?

In this guide

When it comes to mobile broadband there are a large variety of deals out there. To differentiate themselves the mobile providers try to undercut rivals in terms of price, extras, tablet deals and so on. And one of the key selling points is the data usage allowance.

At present unlimited data deals are not available for mobile broadband. The most generous deals have offered 100GB or more, while the frugal amongst you can take deals as low as 500MB, or opt for a pay as you go (PAYG) deal where you top up either per day or per GB.

What can you actually get for your gigabyte?

Firstly, it's important to remember that 1GB is equal to 1000MB (MB - Megabytes). Most forms of data that you will use are going to be measured in MB, with some smaller files measured in Kilobytes (1000KB = 1MB) or even Bytes (1000B = 1KB).

(Bytes are different from bits. A byte is usually a measurement of data storage capacity or file size, whereas a bit is how we measure broadband speed. When buying a new mobile broadband service you'll see a megabyte or gigabyte number showing how much data you can use, and a megabit number showing the approximate speed of the service.)

Secondly, note the below info is only approximate – files are not created equal! Use this information as a guideline to how large files might be, but be careful and keep a close watch on your usage. Don't rely on any usage calculator software, whether it is downloaded as part of your dongle software or from a third party – these don't tend to be accurate, and claiming you used one will be no help as a defence to your mobile broadband service provider if you go over your limit and incur a penalty!

The only way to be sure how much allowance you have left is to check your account online with your mobile broadband service provider. Basically, if you're using a data counter for mobile broadband, don't rely on it.

How much usage do I need?

This will completely depend on how you intend to use mobile broadband. For many mobile broadband users it is a back-up to a fixed-line or business connection: they use a dongle with a laptop to browse the web and download emails when out of the office or on holiday, and not for data intensive tasks. These users are unlikely to get too close to a 3GB limit, let alone a 50GB one, unless they decide to watch a lot of streamed content (see below) or download massive work files.

However, if you're looking to use mobile broadband as a replacement for fixed-line broadband (where usage limits are far more generous and penalties less severe) you need to be careful.

Work out what you're going to be downloading from our table below and also make sure to check out the excessive usages you may be saddled with, just in case. Even as your main source of broadband a 15GB limit per month can be sufficient – just take note of the really data-intensive uses below, and if you're concerned keep close tabs on your account.

Fair usage and excessive usage policies: charges

The cost of going over your usage limit can vary dramatically between providers on monthly contracts. We're not going to list all of the provider charges here as it's akin to painting the Forth Bridge; no sooner have we updated them than one of the providers decides to change them again.

Suffice it to say, whoever you choose you're going to have to pay more than your usual 'per GB' rate for any excess data you use. On the plus side, of course, mobile broadband providers will always be happy to put you onto a more expensive tariff to give you a larger allowance; they're generous like that...

Mobile broadband usage calculator

As already noted above these are rough estimates based on information gathered from a variety of sources including mobile broadband providers and data published by companies such as Skype. Please read the notes below the table for more detailed descriptions that will help explain the variations in estimates.

1 hour of instant messaging 0.25-1MB
60 web pages 222MB
Download 100 emails 1-10MB
1 hour Skype call 225MB
1 hour Skype video call 350MB
Download 1 photo 0.05-2MB
Download 3 minute MP3 audio file 3-8MB
Download 1 film trailer (720p) 50-100MB
1 software/game download 5MB-50GB
Download 1 film 700MB-8GB
Streaming 1 hour of video (standard definition) 150-350MB
Streaming 1 hour of video (high definition) 1-2GB
Streaming 1 hour of audio 60-200MB

Instant messaging, social networking and surfing the web
Just using the web shouldn't eat into your usage allowance by too much. The average size of a web page is now around 3.7MB so you can get plenty of web browsing done even on plans with small limits.

Remember though that the sizes can vary depending on the content. if you're surfing basic websites without too many images, videos or other content your usage will be very low. Instant messaging is also very light on data usage when it's simply text.

However, many websites now feature streaming audio/video and animations, while many people use social networking and instant messaging to exchange images, video clips etc. If you are visiting a lot of sites that download video clips automatically, you should also make sure you're aware of the amount of data use this can incur (see below).

If you'd like to clamp down on the data used by web sites you can install web browser extensions to block videos, animations and scripts until they are manually requested.

Downloading emails
Don't forget there are two types of email – web-based and software based. If you use a web-based email system such as Hotmail, Yahoo or Gmail, checking your email is just counted as surfing the web (except if you download an attachment – then see below).

If you use a software client, such as Outlook, then you are downloading all that email to your computer – attachments and all – whether you open them or not. The reason the spread is so large is that there is an estimate of how many, and how large, your attachments will be. This will only really be a concern if you receive a lot of large files in your inbox. Regular text emails with no attachments and few embedded images are very small.

Using Skype with mobile broadband
Our estimate of 180MB for 60 minutes is based on data provided by Skype itself. They claim that when making Skype-Skype calls you'll use around 3MB per minute. If you're calling from Skype to a landline that drops to about 1MB per minute. Video calls consume around 500-600Kbps depending on whether it's to a mobile device or computer - that equates to around 225MB of data an hour at the very least.

Downloading software
Here as well you will notice quite large differences in the estimates of how big each type of file will be; this quite simply comes down to the huge variance in the size of software packages.

You'll find a vast number of applications will be under 10MB, however software such as anti-virus tools can be much larger, while complex applications like Microsoft Office or the Adobe suites can easily run up to or over 1GB, and the latest games can be in the region of 50GB. Patches for operating systems and software can also be sizeable, coming in at hundreds of megabytes or more.

However, this is very easy to control as you can always see the size of a file before you download it.

Images can be tiny, and often have to be if used as an avatar on a social networking site or message board (perhaps only a few kilobytes). Large detailed images in high quality formats can run into many megabytes, or even gigabytes, but most of the time images will either be compressed pictures from the web or photos that you upload or download, which are more likely to be a few MB each.

Downloading audio
MP3s are the most common format for digital music files. The variation comes for two reasons – the longer the song and the better quality it is, the bigger it will be. Most clock in around 1-1.5MB per minute. If you download music in a lossless format such as FLAC, WAV or ALAC the file sizes are significantly larger, perhaps 30-40MB per track.

Downloading video
This can be really data intensive, so be careful. While a short clip could be a few megabytes a full DVD quality film could be 1GB or more. HD downloads will be much larger, in the region of several gigabytes. A HD movie trailer just a few minutes long can easily exceed 100MB.

Streaming video
Streaming HD and standard definition video is data intensive. It's tricky to estimate as there are so many video streaming sites, though as a rough guide the BBC says one hour of television from iPlayer will see you downloading anywhere from 50-350MB of data. YouTube uses about 250MB per hour for a 480p video, the default setting.

HD content will obviously use a lot more bandwidth. For example, Netflix HD streams can be anywhere from 1GB an hour to over 2GB an hour, so a single movie could run through the entire monthly data allowance for cheap mobile broadband packages.

Streaming audio
Audio is less data intensive but can still add up. Our data usage estimation is based on Spotify.

Spotify offers a variety of quality levels, with the lowest using about 50MB an hour and the highest running to almost 150MB. However you also need to account for the P2P service Spotify uses to bolster its network. Each person running desktop Spotify is also hosting a peer-to-peer service and this can add 10-50MB per hour. You can block the P2P feature using a firewall.

All in, Spotify can use 200MB per hour so you could burn through 1GB data in a single working day. To make it last use the lowest quality setting and disable P2P.

What the mobile broadband provider websites say

To give you an idea of how the companies that sell you your mobile broadband products look at data usage, here is a summary of information taken from their sites*:


The EE data calculator is a funky wheel thing that contains pretty good information, if not especially precise (for example, it suggests that if you just stream "TV shows" on mobile broadband every week you should get a 5GB allowance. That's a bit vague for our liking).


O2 had an online calculator that offers help in working out what kind of mobile broadband tariff to go for - kind of. As an example, if you’re going to send and receive 'lots' of emails, download songs 'now and then' and also download video clips 'quite a bit', then you’ll only need around 500MB of monthly data usage. However, add on 24 hours of web browsing a week, 5 hours of streaming video clips and lots of app use and it adds up to more like 2GB. It's a bit vague, but better than some! But last time we checked the calculator page was broken...


Three has vastly improved its data calculator in recent times, with sliders for everything from browsing the web to streaming and downloading video. Again the estimates are pretty high, but as Three is pretty generous with its data limits for the price we're prepared to forgive them in the most part.


Vodafone has also improved from a useless list to a five-slider internet calculator. These sliders cover all the main bases and are simple to understand, while the estimated usages are pretty much within our suggested boundaries. Good job!

*Data accurate as of November 2017.

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