When your phone or computer uses the internet it sends and receives email, digital video, music, photographs and any other information as data.
Apps such as Google Maps also use data when they download information from the internet, and you also send and receive data when you make changes to a shared calendar that is synced online.
You'll tend to use data fairly often when using a computer or mobile phone, and your broadband or mobile contracts typically allow you to use a certain amount of data per month (known as your data allowance), although some broadband contracts let you access unlimited data.
How much data can I use?
Data is measured in kilobytes (KB), megabytes (MB) and gigabytes (GB). There are 1,024KB in 1MB and 1,024MB in 1GB.
Broadband and mobile phone plans come with a monthly data usage limit, unless you're on an plan with unlimited data, such as BT Superfast Fibre.
Exceed your monthly data allowance and you’ll be charged extra - most of our broadband plans come with unlimited data so you don't have to worry about this. Our Superfast Fibre Essential plan comes with 30Gb data: exceed this and you'll be charged £1.80 per GB or part of each GB.
Go over your monthly BT Mobile allowance and you'll be charged 10p per MB or 35p a minute for calls. If you keep going over your allowance it might be worth swapping to a plan with more data.
How much data do I need?
The amount of data you use depends on what you’re doing and how much time you spend doing it.
Sending an email or using an IM service like WhatsApp Messenger uses relatively little data. Downloading a music track uses a moderate amount, and streaming or downloading a HD movie uses the most. Here are some examples of typical data use:
BT data is usually measured in GB. BT, like other broadband providers, offers packages with different data allowances.
Mobile phone data
Mobile phone data is typically measured in MB and GB. Networks offer a range of tariffs with different data allowances. BT Mobile has a range of SIM-only deals to suit all types of user.
If you have a 4G SIM and mobile phone you should ensure the data allowance is higher than normal. 4G doesn’t use more data than 3G, but because it’s faster than 3G and streams HD video more smoothly, you may find you use your phone for things that use more data.
How do I know how much broadband data I’ve used?
BT Broadband customers can log on to www.bt.com/mybt to view data use and check how much is remaining.
Read more in our article: Discover the easy way to manage your BT account with the My BT app.
How do I know how much mobile data I’ve used?
BT Mobile customers can log in to www.bt.com/mymobile to see a detailed view of usage.
How can I use less data on my home broadband and mobile phone?
1: Download with caution
Be careful about the things you use your computer or mobile phone for.
Broadband users without an unlimited allowance should take care when downloading large files such as movies or TV series, particularly if they are in high definition: HD files are bigger and use more data.
Mobile phone users should watch out if streaming video using BBC iPlayer or music using Spotify and YouTube.
2: Use wi-fi on mobile
Connect your mobile phone to wi-fi hotspots when out and about to go online without using data.
3: Turn off push email on mobile
Push email allows emails to be sent directly to your phone from the server as soon as they arrive in your inbox. It's useful in that you'll never miss a message, but each time an email is ‘pushed’ you use up part of your data allowance.
4: Deactivate automatic app refresh on mobile
Many apps are updated frequently and if you aren’t careful, will update in the background and use data without you realising.
Android: Launch the Google Play Store. Go to Menu – Settings. Look for Auto-update apps and choose Auto-update apps over wi-fi only.
What about using data abroad on your mobile phone?
When you leave the UK you are no longer connected to your home network, and you will be charged for all data usage. This is known as ‘data roaming’ because you are roaming away from your network.
BT Mobile's Roam Like Home lets you use your monthly data, calls and text allowance in 47 EU destinations*. This means you can talk, send texts and use the internet just like you would in the UK, without worrying about facing a hefty bill when you come home.
Go over your allowance and you'll be charged at BT Mobile's standard rate.
Roam Like Home doesn't cover use of your phone in non-European countries like Japan, Australia and Canada.
How to turn data roaming off
If you are visiting a country not covered by Roam Like Home, turn off data roaming on your smartphone. Most phones have it switched off by default, but double-check the settings to make sure your phone is not capable of accessing the internet via the network connection. You can still use wi-fi.
- Android: Tap Settings - Network & Internet - Mobile network - Roaming. The interface on Android devices varies between handset manufacturers, so if you can’t find it, check the manufacturer’s website.
- iPhone: Discover how to turn off roaming here. The screenshots refer to a US device, so look for ‘Mobile Data’ instead of cellular.
- Windows Phone: Swipe left to get to the Applications List. Tap Settings - Mobile Network, look for the Data Roaming Options box and select Don't Roam.
If you are heading abroad and plan on using your mobile phone, check out our article: How to prepare your smartphone for holiday.
*Roaming Zone 1a: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Isle of Man, Italy, Latvia, Lithuania, Luxembourg, Malta, Monaco, Netherlands, Poland, Portugal (Incl. Azores & Madeira), Romania, Slovakia, Slovenia, Spain, Sweden, Vatican City. Roaming Zone 1b: Canary Islands, French Guiana, Gibraltar, Guadeloupe, Guernsey, Iceland, Jersey, Liechtenstein, Martinique, Mayotte, Norway, Reunion, Saint Barthelemy, Saint Martin, San Marino, Switzerland