In the past when choosing a mobile phone tariff, you'd look at the number of minutes and texts on offer, but now there's a third factor worth considering - data. But what is data and how much do you need?

What is data?

Data is a process of sending and receiving information over your phone network. You don’t use data to make calls, but you use it to send emails, browse the internet, upload photos or download apps, when you aren't on a WiFi network. Sony Xperia S web shortcut

Not all phones need or use data, but if you're planning on using a smartphone or feature phone that offers even very basic social networking and web access, you'll want to think about including some form of data allowance in your plan. Otherwise unauthorised data charges can be high.

Different applications will require different amounts of data, for example plain text emails are far less data hungry than watching You Tube videos. Similarly the frequency at which your phone is set to check for updates - whether that means new emails, social network updates or weather information - also contributes to data use. The more frequently you check the more data you'll use.

If you don't keep an eye on your data use it can easily get out of control, which can lead to expensive phone bills, but there are ways to minimise how much data you use, which we'll cover later.

WiFi and Data are different. Browsing over an open Wi-Fi network or your home network doesn't use up your data allowance (unless otherwise indicated) and you can access the internet and emails over a Wi-Fi network even if you don't have mobile signal.

Types of data connectivity

Smartphones can connect to the internet using a variety of different methods over a mobile network. The indicator at the top of your phone (right) tells you what type of connection you are using. The faster the connection type, the quicker you can download (or upload) information. Note: The speed of a data connection does not affect the amount of data used.

  • GPRS: often marked on a phone's display with a 'G' is the slowest form of iPhone Edge Symboldata connectivity and usually a phone resorts to this method if it cannot find anything faster.
  • EDGE: usually denoted with an 'E' is quicker than GPRS
  • 3G: offers around double the speed of EDGE
  • HSDPA:(denoted by an 'H') is an enhanced version of 3G and the current standard for phones in the UK
  • HSPA+: Rolling out this summer from Three, offering faster speeds. It is sometimes called 3.5G
  • 4G: is even faster, but is currently being trialled so isn’t widely available yet

Choosing a data bundle

All mobile networks offer tariffs with various amounts of data included, usually in increments of: 100MB, 250MB, 500MB, 750MB, 1GB, 2GB and Unlimited.

Depending on the network and the tariff, the data options available may vary, but how do these numbers work out in the real world?

  • 100MB: eight You Tube videos, 400 emails, 360 web pages
  • 250MB: 20 You Tube videos, 1000 emails, 900 web pages
  • 500MB: 40 You Tube videos, 2000 emails, 1800 web pages
  • 750MB: 60 You Tube videos, 3000 emails, 2700 web pages
  • 1GB: 80 You Tube videos, 4000 emails, 3600 web pages

Before you sign up to a contract think about how often you use your phone. Are you a commuter who uses your phone for two hours a day five days a week for email, browsing the internet and the odd video? If so opt for a minimum of 500MB. However, if you only use your phone to access the internet at the weekend you may be able to get a away with 250MB. If you're going to be streaming from Spotify and need push email on all the time opt for 1GB at least.

If you are unsure T-Mobile US has a very useful data calculator.

If you know you'll be using a lot of data, two major carriers offer unlimited data with no cap or extra charges. T-Mobile’s The Full Monty offers unlimited data on plans from £36-a-month and up on 24 month contracts. Three offers the Unlimited Internet Plans and The One Plan with prices starting from £15-a-month on a 24-month contract.

Exceeding your data allowanceVodfone data warning

From time to time, you might exceed your daily/monthly data allowance, in which case you’ll accrue extra charges.

Different networks treat excess data usage differently and the cost of extra data can vary. Some networks offer data bundles on PAYG, which are worth checking out too. Here's a list of data charges from the main UK networks, this list isn't exhaustive and may change, so it's always worth checking with your network operator.

If you become close to using your data allowance you should receive a warning text from your network operator (right).

  • O2 PAYG: 1p per 3KB up to the tune of 50MB in a day and up to £1 per day
  • O2 Contract: £3.06 per 1MB of excess data used [LINK]
  • Orange PAYG: £1 bundle for all day mobile internet access. £2 daily capped rate
  • Orange Contract: Orange charges £1 or 61p per day for up to 25MB of usage or a maximum of 500MB in a single month, or £3.06 per MB up to £1.54 day, subject again to a 25MB data charge [LINK]
  • T-Mobile PAYG: £1 a day [LINK]
  • T-Mobile Contract: £1.02 a day maximum on plans when internet isn’t included [LINK]
  • Vodafone PAYG: Pay as you browse costs £1 a day for 25MB and excess data costs equate to £1 for 25MB of data
  • Vodafone Contract: Outside of the carrier’s Web Packs, exceeding a tariffs data cap results in automatic billing of £5 and an addition 250MB of data allowances included. Pay as you browse costs £1 a day for 50MB [LINK]
  • Three PAYG: Excess mobile data usage equates to 11p per 1MB of excess data. Range of add-ons available [LINK]
  • Three Contract: Unlimited on The One Plan and Ultimate Internet Plans. Extra data use blocked on Essential Internet, then £2 for 250MB or £5 unlimited for 30 days. Excess mobile data usage on SIM Only, Essential and Ultimate plans is fixed at 10p per 1MB of excess data. [LINK]

Data monitoring

Modern smartphones let you see how much data you are using on your phone, the exact settings vary per phone. On the iPhone go to Settings - General - Usage - Cellular Usage.

If you've got an Ice Cream Sandwich enabled Android phone got to Settings - Data Use. On a BlackBerry go to Device and Status Information and type the word buyr and an extra menu called Buyer's Remorse appears at the bottom.

There are a number of applications and services that allow you to monitor or minimise how much data your phone is using which helps to avoid any unwanted excess charges.

It's good to shop around, read reviews and search for terms like 'data monitor' to find suitable applications. Onavo Extend for iOS and Android actually helps compress content so that you use less data without changing your browsing habits, it's worth checking out at the very least.

Top tips for managing data use on your smartphone

  • Before you sign up to a contract work out how much data you will need and then add a little extra
  • If you are already on a tariff and you don't have enough data then contact your network operator. You may need to upgrade your tariff or buy a bolt-on
  • Think before you send an email or browse a web page. Can it wait until you are on WiFi?
  • Regularly check your data use
  • Turn off applications that use data in the background. Such as auto sync for email and Twitter
  • Download podcasts, music and apps over WiFi
  • Consider an unlimited data package from Three or T-Mobile