Orders of magnitude (length)

The kilometre (SI symbol: km; or ), spelt kilometer in American English, is a unit of length in the International System of Units (SI), equal to one thousand metres (kilo- being the SI prefix for ). It is the preferred measurement unit to express distances between geographical places on land in most of the world; notable exceptions are the United States and the United Kingdom where the statute mile is used.

thumb|upright=1.35|Different lengths as in respect to the electromagnetic spectrum, measured by the metre and its derived scales. The [[microwave is in-between 1 metre to 1 millimetre.]]

thumb|330px|Different lengths with respect to the electromagnetic spectrum. The [[microwave spans from 1 metre to 1 millimetre.]]

The micrometre (or micrometer in US spelling; symbol: μm) is a unit of length in the International System of Units (SI) equalling (SI standard prefix "micro-" = ); that is, one millionth of a metre (or one thousandth of a millimetre, , or about ). Also known as a micron.

The decimetre (' in American English; symbol: dm') is a unit of length in the International System of Units, equal to one tenth of a metre, ten centimetres, one hundred millimetres, and 3.937 inches.

The picometre (international spelling as used by the International Bureau of Weights and Measures; SI symbol: pm) or picometer (American spelling) is a unit of length in the International System of Units (SI), equal to , or one trillionth of a metre, which is the SI base unit of length.

The hectometre (SI symbol: hm), spelled hectometer in American English, is a unit of length in the International System of Units (SI), equal to one hundred metres and to one tenth of a kilometre. The word comes from a combination of "metre" and the SI prefix "hecto-", meaning "hundred". It is not commonly used in English. A football field (either soccer or American football) is approximately 1 hectometre in length. The hectare (ha), a common metric unit for land area, is equal to one square hectometre (hm2).

A decametre (International spelling as used by the International Bureau of Weights and Measures and by most English speaking countries, United States spelling dekameter), symbol dam ("da" for the SI prefix deca-, "m" for the SI unit metre), is a unit of length in the International System of Units (SI) equal to ten metres.

range of lengths from the subatomic to the astronomical scales

smallest length scales in turbulent fluid flow

particular length or distance determined with the precision of one order of magnitude