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 (30 cm) and 600 mm (60 cm). 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.

Basic module

The standard unit of ISO 2848 is a basic module, a length of Vorlage:Convert 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 Vorlage:Pslink), 6, 12, 15, 30 and 60 basic modules. For smaller dimensions, the submodular increments Vorlage:Frac M (see Vorlage:Pslink) and Vorlage:Frac M are preferred.

Metric foot

A metric foot is a nickname for a preferred number length of 3 basic modules (3 M), or Vorlage:Convert. The 300 mm (30 cm) metric ruler was a similar length to the traditional imperial one-foot ruler. A metric foot is Vorlage:Convert shorter than an imperial foot.

Although the term "metric foot" is still occasionally used in the United Kingdom, in particular in the timber trade, dimensions are most likely to be quoted exclusively in metric units today.

The sizes of the studios at BBC Television Centre in London, which opened in 1960, are specified and measured in metric feet, in contrast to film stages where imperial feet and inches prevail.

Metric inch

A metric inch is a nickname for a preferred Vorlage:Frac subdivision of an ISO 2848 basic module, or Vorlage:Frac of a metric foot measuring Vorlage:Convert. A metric inch is Vorlage:Convert shorter than an inch.

The term was similarly used to refer to the historical Soviet Bloc practice of spacing integrated circuit pins at Vorlage:Frac of a 25 mm "metric inch" length, instead of the western practice of Vorlage:Frac of an imperial inch.

Further reading

• British Standard BS 6750: Modular coordination in building.
• Martin Kempton: An unofficial history of Television Centre
• A similar naming and metric rounding has been done for various measures called a "Metric mile"
• The Pied was used in France between 1812 and 1839, which was Vorlage:Frac of a metre