The iPad and the iPad mini will both be updated this evening, but which size is more convenient? / REUTERS/Robert Galbraith

The iPad and the iPad mini will both be updated this evening, but which size is more convenient? David Phelan explores the options

In the next few hours, Apple will announce its latest iPads. It’s less than four years since the first iPad was launched, when nobody quite knew what it was for but lots of people knew they wanted one anyway. Since then the iPad 2, and the third and fourth generation models have appeared, with improved screens, processors and slightly reduced prices.

(Click here to read our full guide on what to expect from this evening's announcements)

And this time last year, Apple announced a smaller version, the slim, light iPad mini. Much cheaper than the full-size model, it quickly proved popular, even though there were, and are, much cheaper tablets on the market.

So which is right for you?

In almost every way, the iPad mini is the winner. It’s lighter (so light you need to pick it up to appreciate it) slimmer and narrower. Compare it to other similarly sized tablets and it’s a clear winner against those rivals in some ways, too.

Tablets like the Amazon Kindle Fire HDX and Google Nexus 7 are very good, but their displays measure seven inches where the iPad mini has a 7.9-inch display. Now 0.9 inches may not sound much, but it means the screen area is massively enhanced by 34 per cent. Although if you’re watching widescreen video, the black bars on either side mean the screen difference is minimal.

The iPad mini scores highly for size because it has a very thin bezel at its sides. This is possible because of something called thumb rejection: if your thumb is resting on the edge of a touchscreen, most tablets will recognise it. The iPad (mini and full-size) has special software which knows when to discount an extra touch.

However, the iPad mini has an Achilles’ heel – the screen resolution is much lower than its rivals. It’s the same number of pixels as on the iPad 2, but it’s not a patch on the Nexus 7 or Kindle Fire HDX.

But by the end of the evening, the Retina display on the iPad mini may have been announced. It will almost certainly be included and then, screen-wise, Apple will be back in the game.

There’s also the question of price. It’s significantly more expensive than Google’s or Amazon’s models, though the build quality is certainly better.

The full-sized iPad features a 9.7-inch screen and a Retina display.

The styling is also better than the full-sized iPad, though this is likely to change in the next few hours, too. Because the fifth-generation iPad is likely to take design notes from the smaller model, with boxier edges and new colour options.

So why would you choose the bigger iPad? I mean, it’s just heavier and pricer, isn’t it?

Well, it is, but the bigger screen, already a gorgeously high-resolution Retina display, makes movie playback look fantastic and it’s certainly easier to watch for longer at this size. BBC iPlayer really shines.

And it’s pretty likely that the bigger iPad will have the splendid Touch ID fingerprint sensor just launched for the iPhone 5s. It may sound like a gimmick, but launching a device by just resting your thumb on the home button is intimate and enjoyable. And it means you no longer have to type in your password every time you buy music, movies or apps from iTunes.

So the bigger iPad will be more easily secure than the littl’un. And it’s likely to feature a faster processor than the smaller iPad mini – though frankly neither will be dawdlers.

Assuming the mini does win the Retina display upgrade, the benefits of the smaller tablet will make it hard to beat making it, just, the winner.

The screen on the iPad mini is 7.9-inches across, though its PPI currently lags behind its rivals. This is expected to change after today's announcements.