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Contents

Base Units

Chapter:
Units of Measure
Author(s):

Phil B. Fontanarosa

and Stacy Christiansen

Base Units

The SI is based on 7 fundamental units (base units) that refer to 7 basic quantities of measurement (see the tabulation below). These units form the structure from which other measurement quantities are composed.

Quantity

Base Unit Name

SI Unit Symbol

Length

meter

m

Mass

kilogram

kg

Time

second

s

Electric current

ampere

A

Thermodynamic temperature

kelvin

K

Luminous intensity

candela

cd

Amount of substance

mole

mol

Although not included among the 7 base units, the liter is widely used in the SI as a fundamental measure of capacity or volume. The liter is the recommended unit for measurement of volume for liquids and gases, whereas the cubic meter is the SI unit of volume for solids. Although the kelvin is the SI unit for thermodynamic temperature, the degree Celsius is used with the SI for temperature measurement in biomedical settings.

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