An architect's scale is a specialized ruler. It is used in making or measuring from reduced scale drawings, such as blueprints. It is marked with a range of calibrated scales (ratios). A ruler is an instrument used in geometry and technical drawing to measure short distances and/or to rule straight lines. ... Modern blueprint of the French galleon La Belle. ... In number and more generally in algebra, a ratio is the linear relationship between two quantities of the same unit. ...

The scale was traditionally made of wood but for accuracy and longevity the material used should be dimensionally stable and durable. Today they are now more commonly made of rigid plastic or aluminium. Depending on the number of different scales to be accommodated architect's scales may be flat or shaped with a cross-section of an equilateral triangle. Longevity is defined as long life or the length of a persons life (life expectancy). ... Durable - the ability to endure. ... General Name, Symbol, Number aluminium, Al, 13 Chemical series poor metals Group, Period, Block 13, 3, p Appearance silvery Atomic mass 26. ...

United States and Imperial units

In the United States, and prior to metrification in Britain, Canada and Australia, architect's scales are/were marked as a ratio of x inches-to-the-foot. For example one inch measured from a drawing with a scale of "one-inch-to-the-foot" is equivalent to one foot in the real world (a scale of 1:12) whereas one inch measured from a drawing with a scale of "two-inches-to-the-foot" is equivalent to six inches in the real world (a scale of 1:6). Speedometer gauges on a car showing the speed of the vehicle in miles and kilometres per hour. ... Mid-19th century tool for converting between different standards of the inch An inch is an Imperial and U.S. customary unit of length. ... A foot (plural: feet) is a non-SI unit of distance or length, measuring around a third of a metre. ...

Typical scales used in the United States are:

• Full scale, with inches divided into sixteenths of an inch

The following scales are generally grouped in pairs using the same dual-numbered index line:

• three-inches-to-the-foot (1:4) / one-and-one-half-inch-to-the-foot (1:8)

• two-inches-to-the-foot (1:6) / one-inch-to-the-foot (1:12)

• three-quarters-inch-to-the-foot (1:16) / three-eighths-inch-to-the-foot (1:32)

• one-half-inch-to-the-foot (1:24) / one-quarter-inch-to-the-foot (1:48)

• one-eighths-inch-to-the-foot (1:96) / one-sixteenths-inch-to-the-foot (1:192)

Metric units

Architect's scale rulers used in Britain and other metric areas are marked with ratios without reference to a base unit. Therefore a drawing will indicate both its scale and the unit of measurement being used.

In Britain the standard units used on architectural drawings are the SI units millimetres (mm) and metres (m), whereas in France centimetres (cm) and metres are most often used. The International System of Units (abbreviated SI from the French language name Système International dUnités) is the modern form of the metric system. ... A millimetre (American spelling: millimeter, symbol mm) is an SI unit of length that is equal to one thousandth of a metre. ... The metre (Commonwealth English) or meter (American English) (symbol: m) is the SI base unit of length. ... The metre, or meter (symbol: m) is the SI base unit of length. ...

In Britain, for flat rulers, the paired scales often found on architect's scales are:

• 1:1 / 1:100

• 1:5 / 1:50

• 1:20 / 1:200

• 1:1250 / 1:2500

and for triangular rulers:

• 1:1 / 1:10

• 1:2 / 1:20

• 1:5 / 1:50

• 1:100 / 1:200

• 1:500 / 1:1000

• 1:1250 / 1:2500

See also

• Engineer's scale