"Metric foot" redirects here. For the poetical term, see foot (prosody).
While those dimensions equate to 30 cm and 60 cm respectively, it is the use of millimetres which is significant.
The numbers 300 and 600 were chosen because they are preferred numbers due to their large number of divisors – any multiple can be evenly divided into 2, 3, 4, 5, 6, 10, 12, 15, 20, 25, 30, etc., making them easy to use in mental arithmetic. This system is known as "modular coordination". A related standard is British Standard 6750.
The standard unit of ISO 2848 is a basic module, a length of 100 millimetres (3.937 in) which is represented in the standards by the letter M. Adherence to the standard means that major dimensions such as grid lines on drawings, distances between wall centres or surfaces, widths of shelves and kitchen components are multiples of the basic module. As dimensions increase, preference is given to lengths which are multiples of 3 (see metric foot), 6, 12, 15, 30 and 60 basic modules. For smaller dimensions, the submodular increments 1⁄4 M (see metric inch) and 1⁄2 M are preferred.