System of units of measurement

Eventually cubits and strides gave way to "customary units" to meet the needs of merchants and scientists.

The preference for a more universal and consistent system only gradually spread with the growth of international trade and science.

The French Revolution gave rise to the metric system, and this has spread around the world, replacing most customary units of measure.

Gaussian units have only length, mass, and time as base quantities, with no separate electromagnetic dimension.

In the metric system and other recent systems, underlying relationships between quantities, as expressed by formulae of physics such as Newton's laws of motion, is used to select a small number of base quantities for which a unit is defined for each, from which all other units may be derived.

Traditional Burmese units of measurement are used in Burma, with partial transition to the metric system.

There is also considerable use of imperial weights and measures, despite de jure Canadian conversion to metric.

A number of other jurisdictions have laws mandating or permitting other systems of measurement in some or all contexts, such as the United Kingdom whose road signage legislation, for instance, only allows distance signs displaying imperial units (miles or yards)[1] or Hong Kong.

At retail stores, the litre (spelled 'liter' in the U.S.) is a commonly used unit for volume, especially on bottles of beverages, and milligrams, rather than grains, are used for medications.

Some other non-SI units are still in international use, such as nautical miles and knots in aviation and shipping, and feet for aircraft altitude.

Multiples and submultiples of metric units are related by powers of ten and their names are formed with prefixes.

This relationship is compatible with the decimal system of numbers and it contributes greatly to the convenience of metric units.

While some steps towards metrication have been made (mainly in the late 1960s and early 1970s), the customary units have a strong hold due to the vast industrial infrastructure and commercial development.

have been identical since the adoption of the International Yard and Pound Agreement; however, the US and, formerly, India retained older definitions for surveying purposes.

While no longer in official use, some of these customary systems are occasionally used in day-to-day life, for instance in cooking.