Last edited 22 Jan 2020

# Dimension

A dimension is a derived unit used to measure a physical quantity such as length, width, height, distance, area, volume, mass and time.

Some of these units, such as area, can be obtained by the multiplication of two other dimensions, so for example (a x b) gives the area ab. Other measurements such as volume can be established by combining three linear measurements. The volume of say, a cylinder may be given by multiplying the area by the height (a x b x h).

A straight line has one dimension; an area has two dimensions and a volume has three.

Measuring velocity requires combining dimensions of length and time. Measuring force also requires combining various dimensions.

In construction, the dimensions most used are those concerning length to provide other dimensions of height, distance, area and volume. Measuring time is also important in construction, as is mass.

Dimensions are critical for co-ordinating building components and ensuring each fits correctly in its allocated place in a construction. Dimensionally co-ordinated products allow designers to select items which they can be confident will fit together (co-ordinate) dimensionally with the structure and other components to accepted tolerances.

Measurements are often included on drawings to give an overall understanding of size, or by wave of instruction to help workers setting out a project or manufacturing components.

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