The easiest way to measure for new doors is to measure your old ones. A door should be 5mm less than the overall height of the cabinet and 4mm less than the overall width, this is to allow for clearance between adjacent doors and the worktop.

If your cabinet is 720mm high and 500mm wide then the required door size is 715mm x 496mm.

STANDARD CABINET HEIGHTS EXCLUDING LEGS

Base units 720mm -  Belfast sink base 460mm -  Dropped pan drawer base 575mm -  Bridging units 290mm and 360mm 

Wall units 575mm, 720mm and 900mm

Midi Tall units 1250mm -  Appliance Housing and Larders 1825mm, 1970mm and 2150mm

Cabinet legs are usually 150mm giving a finished height of 870mm on a standard base cabinet.

STANDARD WIDTHS

WIDTHS both Base and Wall Cabinets. 150mm, 300mm, 400mm, 450mm, 500mm, 600mm, 700mm, 800mm, 900mm, 1000mm, 1100mm and 1200mm.

DEPTH OF CABINETS These do vary from different manufacturers. The sizes shown are doorbox cabinets which are European standard sizes.

Base cabinets 560mm deep. Reduced base cabinets 300mm deep. Wall cabinets 300mm deep.

Some Kitchen retailers sell a non standard size cabinet that only their own doors will fit, IKEA and WICKES are good examples.