Tim Cook shows off the watch with model Christy Turlington / Getty

New feature should let users try out the different sizes, without printing out paper models

The Apple Store app has been updated for the release of the Apple Watch, allowing users to see just how much each model costs as well as letting them try out the different sizes on their wrists.

The watches come in two versions — 38mm and 42mm — and each is represented at its actual size on the app. Potential Apple Watch customers can then hold up the app to their wrist and decide if they want the smaller or bigger watch.

When the same problem of being unable to decide which size to buy with the iPhone, Apple fans came up with solutions including print-out versions of the phone, allowing you to try which would be the best size.

The updated app also includes information on the new watch, and the option to look through the dozens of different versions of the watch. The app gives all the prices for the different strap and watchface combinations, which run from £299 to £13,500.

Customers will be able to try on real versions of the watch in Apple Stores from April 10, when pre-orders will open and Apple will begin its “Preview” stage. The shops will then go on sale on April 24.