SI base units

Quantity SI
Base Unit English
Equivalent Definition

length meter (m) 1 m = 39.36 in distance travelled by light in a vacuum in 1/299792458 of a second
mass kilogram (kg) 1 kg = 2.2 lbs mass of a platinum/iridium cylinder kept in Paris
time second (s) time required for 9,192,631,770 cycles of the 3.26 cm microwave line of cesium-133.
temperature kelvin (K) °F = 1.8(^oC)+32 K = °C + 273.15 273.16 degree K is assigned to the triple point of water (where vapor, liquid, and ice are at equilibrium)

electric current ampere (A) amount of current flowing through each of two long parallel wires separated by 1 m that results in a force of 0.2 micronewtons per meter along the wires

luminous intensity candela (cd) luminous intensity of 1/600000 m² of a radiating cavity at the melting point of platinum (2042 K)

amount of substance mole (mol) amount of substance that contains the same number of particles as the number of atoms in a sample of pure carbon-12 weighing exactly 12 g

General Chemistry Online! SI base units

Quantity	SI Base Unit	English Equivalent	Definition
length	meter (m)	1 m = 39.36 in	distance travelled by light in a vacuum in 1/299792458 of a second
mass	kilogram (kg)	1 kg = 2.2 lbs	mass of a platinum/iridium cylinder kept in Paris
time	second (s)		time required for 9,192,631,770 cycles of the 3.26 cm microwave line of cesium-133.
temperature	kelvin (K)	°F = 1.8(^oC)+32 K = °C + 273.15	273.16 degree K is assigned to the triple point of water (where vapor, liquid, and ice are at equilibrium)
electric current	ampere (A)		amount of current flowing through each of two long parallel wires separated by 1 m that results in a force of 0.2 micronewtons per meter along the wires
luminous intensity	candela (cd)		luminous intensity of 1/600000 m² of a radiating cavity at the melting point of platinum (2042 K)
amount of substance	mole (mol)		amount of substance that contains the same number of particles as the number of atoms in a sample of pure carbon-12 weighing exactly 12 g