If you're heading off on holiday, you might be worrying about what your phone bill is going to look like at the end of the month thanks to data roaming charges. Here, we show you how to avoid data roaming charges on your iPhone while you're abroad.

With reports suggesting that the average smartphone owner uses about 500MB of data per month, it's easy to see how phone bills can rack up while abroad, especially with data roaming charges (the charges that come from using your iPhone on another network for a short period) currently at the high price of £7.50/MB outside of Europe. According to price comparison site uSwitch, UK holidaymakers spend an average of £120 extra on their mobile phone each time they go abroad.

So, how can you avoid data roaming charges while you're abroad?

First things first, it's important to remember that your unlimited data allowances only apply to usage in the UK. So, one of the easiest ways to avoid data roaming charges is to connect to WiFi where possible. Unless the particular WiFi hotspot charges for access (you will probably have to sign in or register to access WiFi of this kind, so you'll be notified if any charges apply) you won't be charged for downloading data over that connection.

Change your settings to avoid data roaming charges

Before you head off abroad, check your network settings. To do this, go to Settings > General > Cellular. Here, you'll see three sliders: Cellular Data, Enable 3G and Data Roaming.

If you turn off Cellular Data, you'll be limiting all data to WiFi. If you want to make sure you don't spend any extra cash on data while you're abroad, slide this to off.

If you want to have a little more freedom, you can turn off the Data Roaming slider. This will help you avoid charges by restricting your access to the cellular data when you're abroad. If you try to use an app that requires internet access while data roaming is turned off, it will prompt you to manually switch data roaming back on unless you're connected to WiFi.

Get a data bundle to avoid unexpected charges

Some network operators offer the option to sign up to a flat-rate or capped data package, but you'll need to check that they work in the country you're travelling to before arriving at your destination. Contact your network operator to find out more about these packages.

Get a new SIM card to avoid excessive data charges

Another option is to get a new SIM card for use abroad. If you've got an unlocked iPhone, you'll be able to get hold of a suitable SIM card from UK company Dataroam, which has a range of pay-as-you-go and 30-day plans for use in a variety of different countries. The company claims that you can save over 90% on international roaming charges by using its SIM cards while abroad.

Most UK phone networks lock their iPhones in order to prevent customers from using alternative SIM cards, but you can ask the network provider to unlock your iPhone. This could prove difficult, however, as they are not always keen on you doing so, as having a locked phone forces the user to pay their high rates.

However, there are lots of small, independent mobile phone stores and online unlocking specialists who will be able to unlock your iPhone. Unlocking your iPhone shouldn't cause any problems either in the UK or abroad.

Use a MiFi to reduce data roaming charges

Alternatively, if you don't want to (or can't) unlock your iPhone, you could use a MiFi device. MiFi lets you create your own personal WiFi hotspot, which will allow you to run up to five WiFI-enabled devices from that point, coming in handy for groups or families while abroad.

At present, Dataroam is selling the Globalgig International data SIM card and MiFi for £49.99. With it, you get 1GB of 3G data for 30 days, and a reduced charge of 15p/MB for additional data, which is much cheaper than standard network rates abroad.

Compress data to reduce charges while abroad

To reduce data charges while you're out of the country, but also while you're still at home, you can get the free Onavo Extend iPhone app from the iOS App Store. The app promises to increase the amount of data you can get out of your data plan by 500 per cent, by compressing your data and providing a leaner version of the web.

While it doesn't mean you'll get no data roaming charges at all, it does mean that, while you're abroad, you'll be racking up a bill that could be five times smaller than it would have been if you didn't have Onavo Extend.

Plus, Onavo Extend also gives you monthly data usage reports to help you manage your data consumption, too.

Download your maps to save on data charges

Most of the time, if you're abroad, you probably aren't familiar with your surroundings like you are when you're at home in the UK. Therefore, you'll want to whip out your iPhone and use Apple Maps or Google Maps to get around town.

You can cache Apple Maps and Google Maps offline before you head out for the day. If you know where you'll be going, you can search for that area and view it in Apple Maps while you're online, then that data should be stored in the app ready to view when you're offline. You can zoom in and out to see data such as road names too.

As for Google Maps, version 2.0 brings a better offline Maps feature to the iPhone. When you're online, all you need to do is view the area you're planning on visiting, and then, in the search bar type "ok maps". This will bring up a loading screen that'll inform you that you're downloading the data, and then, when you launch the app while you're offline, you'll be able to see the map, as well as data such as road names and attractions, without getting charged to do so.

Alternatively, there are apps you can download such as City Maps 2Go or ForeverMap 2, which will let you view maps offline. They'll set you back a few pounds, though.

Turn your phone off to avoid data roaming charges while abroad

For those of you heading off on holiday, do you REALLY need to use your iPhone? If you can live without Facebook and Twitter for a week, it might be worth taking a break from your iPhone and turning if off altogether.

How much will data cost me while abroad?

Thanks to the EU's rate caps on mobile roaming charges, which were put in place at the beginning of July, using the internet in Europe will cost you less now than it did last year. Next year, it'll get even better. As of July 2014, you'll be able to use your iPhone elsewhere in Europe for the same price as you can at home.

For now, though, data roaming charges are as follows:

O2 currently charges 46p per MB within the EU, and £6 per MB outside of the EU.

Vodafone will charge you 45.9p per MB in the EU or £3 per MB up to 5B in the rest of the world. If you go over 5MB, it'll be £15 per MB. Alternatively, you can opt to take your UK minutes, texts and internet to EU countries for £3 a day with Vodafone EuroTraveller. Vodafone customers will automatically have a spend limit of £42.40 (ex VAT) in both its Europe Zone and Rest of World Zone. Outside of Europe, you can opt in to Vodafone's Data Traveller for £5 per day for 25MB each day you access the internet. However, it's worth highlighting that 25MB of data can be eaten up fast.

Orange customers will be charged 45.9p per MB within the EU, but £8 per MB for the rest of the world.

3 (Three) charges 48.5p per MB in the EU and £3 per MB outside the EU. It offers a Euro Internet Pass, which means you can use the internet for £5 per day.

With EE you have to buy a roaming add-on before you can use the internet while you're away, but it can get rather confusing. If you have a 4G EE phone plan with roaming included you can pay 50p per 2MB for 24 hours, up to 1GB for 30 days for £25 within Europe. If you don’t have roaming included in your EE 4G phone plan 3MB costs £1, up to 200MB for £35 in Europe. It all depends on where you are, with EE. If you're in Japan an add-on costs a staggering £195 for 50MB.

For more details about charges from your network provider you can visit their websites or call them.

(Note - Included EU countries are: Andorra, Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Faroe Islands,'French Guyana, , Finland, France, Germany, Gibraltar, Greece, Guadeloupe, Guernsey, Hungary, Ireland, Iceland, Italy, Isle of Man, Jersey, Latvia, Liechtenstein, Lithuania, Luxembourg, Malta, Martinique, Monaco, Netherlands, Norway, Romania, Poland, Portugal, San Marino, Slovakia, Slovenia, Spain, Sweden and Switzerland.)

Additional reporting from Simon Jary of PC Advisor