Apple's third-generation iPad - the new iPad, reviewed here - is available in the same 16GB, 32GB and 64GB capacities as iPad 2, with no possibility of storage expansion via removable memory.

With the 32GB and 64GB models starting at £479 and £559 respectively, we think most people will be attracted to the cheaper £399 16GB iPad. But with all the HD features Apple has unveiled, how quickly will they find themselves running out of space?

The new iPad has a quad-resolution 2048x1536-pixel screen that will make watching full-HD films an even more tempting proposition. But these videos take up considerably more space than standard-definition (SD) movies.

Apple has promised to start offering 1080p films through iTunes, although we could only find 720p available to buy or rent in the UK at present. Still, at around 4GB for an existing 720p download, there won't be a lot of space on a 16GB model once you've loaded up with a few apps too.

Then there's the new 5Mp rear stills camera, also capable of filming video at 1920 x 1080 resolution. Combined with Apple's very simple to use iPhoto and iMovie for iOS apps, there'll be a lot more creative photography and film making happening on Apple's new iPad. See also: New iPad retina screen - What you need to know

New iPad: Resolutionary gameplay

If you play games on the iPad, be prepared to store them. Existing action games can take many megabyte of storage space. Retina resolution will herald a new wave of ultra-detail games that will almost certainly require more space again on the iPad's flash memory.

Although the new iPad's 4G LTE mobile connection is of no use in the UK for the foreseeable future, it could one day allow faster internet access for streaming or downloading even more high-definition content.

If you use the iCloud service, iTunes-bought content such as music and films can be stored on a compatible iPhone, iPad, iPod or Mac. The media is stored in Apple's cloud and also downloaded (rather than streamed) to any other so-configured Apple devices you own.

Depending on how it's set up, iCloud’s synchronisation of devices will have the potential to consume a large helping of your iPad's storage space.

A free iCloud account offers 5GB of storage space – separate to your music, books or photos – but if you store email up there, for example, you'll quickly use that space up.

It's also important to remember that before you begin filling up your iPad, the operating system and related files will consume a certain amount of storage capacity. Expect to find around 14GB of usable storage for your files on a 16GB iPad, for example.

How much capacity you need for your personal media content – that's your non-synced music, video, films, photos, e-books, documents and email – is of course entirely dependent on your intended use of the iPad.

Remember that broadly speaking, video content is the space hog, followed by music and photos, while text-based documents usually take relatively no space at all.

For new users, bear in mind that whatever you originally bought the iPad for, it's quite likely to expand as you come to realise the device's potential.

Even veteran iPad users might base a purchasing decision on how much space they used up on the iPad 2; in fact, they may find themselves suddenly wanting to use the iPad's full-HD camera and Retina display for editing lots of HD images or watching films.

However, our best advice is to check the size of your current media library in iTunes before you choose which iPad model to buy. Then double it to get an idea of how much space you'll soon need. See also: What's new in iOS 5.1?