Length
Popular quickchoices:
kilometre (km) <> mile (mi)
metre (m) <> yard (yd)
centimetre (cm) <> foot (ft)
centimetre (cm) <> inch (in)
kilometre (km) <> sea mile / nautical mile (NM, nmi)
mile (mi) <> sea mile / nautical mile (NM, nmi)
light year (ly) <> kilometre (km)
![]() |
![]() |
![]() |
*SI (International System of Units):
A modern, coherent system of measurement units, built around seven base units. The SI is officially adopted by almost every country in the world.
*US customary system:
The common measurement system of the United States. This system has derived from the imperial system, but has several significant differences.
*Imperial system:
A British measurement system, first standardized in 1824, based on the standard units yard, pound and gallon.