Measuring the Length

Length: Most commonly the longest dimension of a shape or object. In the International Standard of Units (SI), the standard unit of measuring the length is "Meter". It is the distance between two lines on a bar made of Platinum-Iridium alloy (90% Platinum & 10% Iridium) measured at melting point of ice, located at International Bureau of Weights and Measures, Paris.

Following are the different units of measurement and their equivalent values in meters.

Unit	Symbol	Value in Meters	Examples
Chemistry
Angstrom	Ao	0.000 000 000 1	Diameter of Proton = 10-5 Ao Diameter of Electron = 10-8 Ao Wavelength of Violet Rays = 4 000 Ao Wavelength of Red Rays = 7 000 Ao
International Standard Units – SI Units
Nanometer	nm	0.000 000 001	Generalized Use
Micrometer	micron	0.000 001
Millimeter	mm	0.001
Centimeter	cm	0.01
Kilometer	Km	1 000
Imperial Units – American Units
Point	pt	0.000 35	Length of Football pitch = 120 yd Length of Cricket pitch = 22 yd Average walk in an hour = 1 league
Inch	in / “	0.025 4
Hand	hand	0.101 6
Foot	ft / ‘	0.304 8
Yard	yd	0.914 4
Mile	mi	1 609.344
League	league	4 828.032
Marine Units
Fathom	ftm	1.828 8	Fathoms – Depth of sea at shores Nautical Mile – Navigation, Polar Exploration
Cable	cable	182.88
Nautical Mile	nmi	1 850.745 6
Horse Race Units
Horse Length	horse length	2.438 4	Horse length – Distance between horses in races
Furlong	fur	201.168 0
Land Survey Units
Link	li	0.201 2	Surveyor’s Use
Rod	rd	5.029 2
Chain	Ch	20.116 8
Astronomical Units
Earth Radius	RE	6 370 000	Distance from Earth to 1st nearest star (Sun) = 1 AU 2nd nearest star (Proxima Centauri) = 4.225 ly Center of Milky Way Galaxy = 8 000 pc Center of Andromeda Galaxy (M31) = 800 000 pc
Astronomical Unit	AU	150 000 000 000
Light-year	ly	9 460 000 000 000 000
Parsec	pc	30 840 000 000 000 000