How much data do I need?

Choosing a mobile tariff is difficult enough due to the sheer breadth of choice. But how much data do you need per month? It's easy to underestimate how much you'll use and end up having to top up, paying over the odds in the process. Here we look at how much mobile data video, music, apps, web browsing and email uses, and help you decide how many gigabytes you need.

Although there are unlimited data plans available, these tend to be fairly costly – at least in the UK – and you’re more likely to have a data limit, or cap, of 1GB or perhaps less. There are ways to minimise data use on an iPhone, but how much data is enough? What if you want a 4G plan?

What uses the most mobile data?

Even though we all use our smartphones differently, it’s fairly easy to work out how much data is used by various activities.

How much data do I need: video

Video is the real data hog, eating up hundreds of megabytes at even ‘standard’ quality. Watch an hour-long episode on iPlayer over 3G or 4G and you’ll have burned through around 200MB. In HD, it’s more than double that.

How much data do I need? - iPlayer

If you’re the type to watch a few YouTube videos on the commute home, you’ll very quickly find that you’ve used up your 1GB monthly allowance. So if that's your plan, then download YouTube videos before you set off and save your allowance.

Depending on your mobile provider, you may or may not get a warning to tell you so if your connection doesn’t simply cut of (if you’re on a contract, for example) you might also be faced with a sizeable bill for all the data you’ve downloaded beyond that allowance.

How much data do I need: music

Even listening to music via a streaming service such as Spotify can gobble up a big chunk of data. Streaming ‘Normal’ quality music uses up around a megabyte per minute, and double that for High quality.

So, music isn’t as bad as video, but two hours of High-quality Spotify will have wiped 240MB off your allowance.

How much data do I need: web browsing and apps

Browsing the web can use up more data than you might expect, too. The average web page is now over a megabyte, but it really depends on the websites you visit. Forums, for example, can be lighter on data usage as they’re mainly filled with text. Image and video-heavy pages will obviously use more. Adverts, social media widgets and other interactive objects all use up data too.

Apps can use plenty of data too. Some may have restrictions which prevent them downloading large files over 3G or 4G, forcing you to wait until you have a Wi-Fi connection. Others don’t care about the type of connection and download as soon as an internet connection is available. If you use the Facebook app to browse through people’s photo albums, you might use up a couple of hundred MB per month.

Don’t overlook mapping and navigation apps, some of which download maps on demand over 3G or 4G. Browsing Google Maps in the satellite view, for example, is going to use up more data than the plainer view.

How much data do I need: email

Email uses the least mobile data, but this assumes you’re not downloading large attachments. Merely reading and replying to emails uses only a few kilobytes, and you’ll be hard-pushed to use up a 1GB allowance using email alone.

Mobile data: a warning

Most music and video streaming services adapt their quality to the speed of your connection. This is why a YouTube or iPlayer video can revert to a blocky mess when you have a weak connection, then upgrade to a sharper, higher-quality picture and soundtrack when the connection is better.

So, if you’re in a city centre with a strong 4G connection, you might end up watching the HD version of a video and using up 10x more data than when you’re served the lowest-quality version.

How much data do I need? Bottom line

Unless you use your smartphone or tablet as a mobile office or for constantly watching YouTube videos, there’s every chance you won’t break the 1GB barrier each month.

Some providers, such as EE, have a calculator which helps you work out how much you'll use.

Check and see if your mobile provider has an app which lets you keep track of your data usage. Even if there isn’t, you should be able to log into your account via a web browser and see your usage. It may take a couple of months to find out what you use on average.

How much data do I need?

As long as you have Wi-Fi at home and at work, you won’t actually need to use mobile data very often, and modern smartphones automatically connect to Wi-Fi whenever possible. The majority of people use less than 500MB per month, so if you’re on a 2GB plan or even unlimited, you might be able to save money by switching to a smaller data cap.

In urban areas, there’s a proliferation of Wi-Fi hotspots including at coffee shops, train stations and other public places. If you have BT broadband, you’re entitled to use the hundreds of thousands of hotspots around the world for free, and the same is true of Sky customers with The Cloud’s network of thousands of Wi-Fi access points. Similarly, Virgin subscribers can use Wi-Fi on the London Underground at no extra charge.

Because public Wi-Fi hotspots are often being used by many people at once, there’s little chance of getting enough bandwidth to watch video, but you should be able to get directions on the web and check your email without eating into your mobile data plan. We tested out public Wi-Fi against 3G connections in Central London to find out which is best.

See also: What's the UK's best mobile network?