ISO 2848

International standard ISO 2848 (Building construction - Modular coordination - Principles and rules, International Organization for Standardization, 1984) is an ISO standard used by the construction industry. It is based on multiples of 300 mm and 600 mm. The numbers 300 and 600 were chosen because of their large number of divisors - any multiple of 600 mm can be evenly divided into 2, 3, 4, 5, 6, 8, 10, 12, 15, 20, 24, 25, 30, etc. parts, in other words, they were easy to use in mental arithmetic. This system is known as "modular coordination".

Major dimensions (e.g., grid lines on drawings, distances between wall centres or surfaces, widths of shelves and kitchen components) are multiples of 100 mm, i.e. one decimetre. This size is called the "basic module" (and represented in the standards by the letter M). Preference is given to the multiples of 300 mm (3 M, with the nickname "metric foot" and 600 mm (6 M) of the basic module. For larger dimensions, preference is given to multiples of the modules 12 M (= 1.2 m), 15 M (= 1.5 m), 30 M (= 3 m), and 60 M (= 6 m). For smaller dimensions, the submodular increments 50 mm or 25 mm are used. (ISO 2848, BS 6750)