A report on Unit of measurement

The former Weights and Measures office in Seven Sisters, London
Units of measurement, Palazzo della Ragione, Padua
An example of metrication in 1860 when Tuscany became part of modern Italy (ex. one "libbra" = 339.54 grams)

Definite magnitude of a quantity, defined and adopted by convention or by law, that is used as a standard for measurement of the same kind of quantity.

- Unit of measurement
The former Weights and Measures office in Seven Sisters, London

28 related topics with Alpha

Overall

Countries using the metric (SI), imperial, and US customary systems as of 2019.

International System of Units

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Modern form of the metric system and the world's most widely used system of measurement.

Modern form of the metric system and the world's most widely used system of measurement.

Countries using the metric (SI), imperial, and US customary systems as of 2019.
Arrangement of the principal measurements in physics based on the mathematical manipulation of length, time, and mass.
While not an SI-unit, the litre may be used with SI units. It is equivalent to (10 cm)3 = (1 dm)3 = 10−3 m3.
In the expression of acceleration due to gravity, a space separates the value and the units, both the 'm' and the 's' are lowercase because neither the metre nor the second are named after people, and exponentiation is represented with a superscript '2'.
Cover of brochure The International System of Units
Silicon sphere for the Avogadro project used for measuring the Avogadro constant to a relative standard uncertainty of 2 or less, held by Achim Leistner
Reverse dependencies of the SI base units on seven physical constants, which are assigned exact numerical values in the 2019 redefinition. Unlike in the previous definitions, the base units are all derived exclusively from constants of nature. Arrows are shown in the opposite direction compared to typical dependency graphs, i.e..
Stone marking the Austro-Hungarian/Italian border at Pontebba displaying myriametres, a unit of 10 km used in Central Europe in the 19th century (but since deprecated)
Closeup of the National Prototype Metre, serial number 27, allocated to the United States

The SI comprises a coherent system of units of measurement starting with seven base units, which are the second (symbol s, the unit of time), metre (m, length), kilogram (kg, mass), ampere (A, electric current), kelvin (K, thermodynamic temperature), mole (mol, amount of substance), and candela (cd, luminous intensity).

A baby bottle that measures in three measurement systems—metric, imperial (UK), and US customary.

System of measurement

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A baby bottle that measures in three measurement systems—metric, imperial (UK), and US customary.

A system of measurement is a collection of units of measurement and rules relating them to each other.

Seal of the International Bureau of Weights and Measures (BIPM) – Use measure (Greek: ΜΕΤΡΩ ΧΡΩ)

Metre

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Base unit of length in the International System of Units (SI).

Base unit of length in the International System of Units (SI).

Seal of the International Bureau of Weights and Measures (BIPM) – Use measure (Greek: ΜΕΤΡΩ ΧΡΩ)
Meridian room of the Paris Observatory (or Cassini room): the Paris meridian is drawn on the ground.
Paris Panthéon
Triangulation near New York City, 1817.
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Creating the metre-alloy in 1874 at the Conservatoire des Arts et Métiers. Present Henri Tresca, George Matthey, Saint-Claire Deville and Debray
Closeup of National Prototype Metre Bar No. 27, made in 1889 by the International Bureau of Weights and Measures (BIPM) and given to the United States, which served as the standard for defining all units of length in the US from 1893 to 1960
Gravimeter with variant of Repsold-Bessel pendulum
Artist's impression of a GPS-IIR satellite in orbit.

The SI unit symbol is m.

A scientist stands in front of the Microarcsecond Metrology (MAM) testbed.

Metrology

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Scientific study of measurement.

Scientific study of measurement.

A scientist stands in front of the Microarcsecond Metrology (MAM) testbed.
Computer-generated image realising the international prototype of the kilogram (IPK), made from an alloy of 90-percent platinum and 10-percent iridium by weight
Metrology traceability pyramid
BIPM seal
Overview of a national measurement system

Scientific or fundamental metrology, concerned with the establishment of units of measurement

A kilogram mass and three metric measuring devices: a tape measure in centimetres, a thermometer in degrees Celsius, and a multimeter that measures potential in volts, current in amperes and resistance in ohms.

Metric system

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System of measurement that succeeded the decimalised system based on the metre that had been introduced in France in the 1790s.

System of measurement that succeeded the decimalised system based on the metre that had been introduced in France in the 1790s.

A kilogram mass and three metric measuring devices: a tape measure in centimetres, a thermometer in degrees Celsius, and a multimeter that measures potential in volts, current in amperes and resistance in ohms.
Pavillon de Breteuil, Saint-Cloud, France, the home of the metric system since 1875
The metre was originally defined to be one ten millionth of the distance between the North Pole and the Equator through Paris.
James Clerk Maxwell played a major role in developing the concept of a coherent CGS system and in extending the metric system to include electrical units.

Designed for transnational use, it consisted of a basic set of units of measurement, now known as base units.

The metric length of one kilometre is equivalent to the imperial measurement of 0.62137 miles.

Length

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Measure of distance.

Measure of distance.

The metric length of one kilometre is equivalent to the imperial measurement of 0.62137 miles.

There are several units that are used to measure length.

Measuring tape calibrated in 32nds of an inch

Inch

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Measuring tape calibrated in 32nds of an inch
A fire hydrant marked as 3-inch
Mid-19th-century tool for converting between different standards of the inch

The inch (symbol: in or ″) is a unit of length in the British imperial and the United States customary systems of measurement.

Dimensional analysis and numerical experiments for a rotating disc

Dimensional analysis

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Dimensional analysis and numerical experiments for a rotating disc

In engineering and science, dimensional analysis is the analysis of the relationships between different physical quantities by identifying their base quantities (such as length, mass, time, and electric current) and units of measure (such as miles vs. kilometres, or pounds vs. kilograms) and tracking these dimensions as calculations or comparisons are performed.

Four measuring devices having metric calibrations

Measurement

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Quantification of attributes of an object or event, which can be used to compare with other objects or events.

Quantification of attributes of an object or event, which can be used to compare with other objects or events.

Four measuring devices having metric calibrations
The seven base units in the SI system. Arrows point from units to those that depend on them.
A baby bottle that measures in three measurement systems—metric, imperial (UK), and US customary.
A 2-metre carpenter's ruler
Measurement station C of EMMA experiment situated at the depth of 75 meters in the Pyhäsalmi Mine.

Units of measurement are generally defined on a scientific basis, overseen by governmental or independent agencies, and established in international treaties, pre-eminent of which is the General Conference on Weights and Measures (CGPM), established in 1875 by the Metre Convention, overseeing the International System of Units (SI).

Physical quantity

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Physical property of a material or system that can be quantified by measurement.

Physical property of a material or system that can be quantified by measurement.

A physical quantity can be expressed as a value, which is the algebraic multiplication of a numerical value and a unit.