Cupboard depth is determined by several factors, such as what you intend to store in there. It is generally dependent on which type of cupboard you are building, whether it is a bedroom wardrobe, hall cupboard or pantry. Standard depths exist for wardrobes as most clothing requires a certain amount of space to hang without brushing against the walls or doors.
Wardrobes are 60 cm (24 inches) deep to provide room to hang a shirt or light jacket on a hanger inside. However, larger individuals or those hanging wider clothes like sport coats, winter coats and jackets opt for 70 cm (28 inches) of depth, which also allows for shoe storage under the hanging clothes and storage for shoe boxes, sports gear and other boxed items, like torches and books above the clothing on a shelf over the wardrobe rail.
The hall cupboard, also known as the coat rack, is typically 70 cm (28 inches) deep, which allows for the hanging of large jackets and increases the storage space over and under the cupboard rail. This depth makes storing tool boxes, large winter boots and shoe trees on the floor of the cupboard easier. Most coat cupboards are no deeper than this measurement. Any space gained making the closet deeper is lost because hanging coats take up most of the storage space.
The walk-in wardrobe really has no depth as it is measured in length and width. However, when determining how large to make the walk-in wardrobe, factor in the hanging depth of clothing on the rails, which are typically situated up against the wall. This depth is still 60 cm (24 inches). The shelves in the walk-in wardrobe conversely are 33.7 cm to 37.5 cm (13.5 to 15 inches) deep. This space is accounted for when designing the walk-in closet. Allow 90 cm to 1.2 m (3 to 4 feet) of floor space in front of these shelves and enough width to store all of your items, including clothes.
The pantry is another story. This cupboard is anywhere from 30 to 90 cm (12 to 36 inches) deep. Normally, the pantry is 45 cm (18 inches) deep, which is enough space for storing tins and dry goods and makes accessing them very easy. Reaching over tins to grab items stored deep in your pantry shelves is difficult as is seeing where everything is located. However, deeper pantries allow more storage space.