Map features/Units

Some tags have measurable values. The unit of such a value can be given explicitly as part of the value (e.g. maxspeed=50 mph). If no unit is specified, a default unit will be assumed (e.g. for maxspeed=50, the unit kilometre per hour is assumed). If the unit is different from the default, e.g. in non-metric countries, stating an unit is obligatory.

This article shows which units can be explicitly specified and which default units are implicitly assumed.

Default units

If no unit is explicitly specified, the following units are assumed:

Measure	Default unit	Implicit specification	Example
Length	Metre (meter)	m	width=3 means a width of 3 metres
Distance (land)	Kilometre (kilometer)	km	distance=5 means a distance of 5 kilometres
Distance (sea related)	nautical mile	nmi	seamark:light:range=3 means a distance of 3 nautical miles
Speed	Kilometres per hour	km/h	maxspeed=100 means a speed limit of 100 kilometres per hour
Weight	Tonne (metric ton)	t	maxweight=3.5 means a weight limit of 3.5 tonnes (3500 kg)

Explicit specifications

The following units can be explicitly specified by adding them after the numeric value, separated by a space (with the exception of the combined specification of feet and inches):

Measure	Explicit specification	Unit	Example	Aliases (Highly Discouraged)	Conversion to default unit
Length or Distance	m	Metre (meter)	height=3 m	metre, metres, meter, meters	-
	km	Kilometre (kilometer)	width=0.2 km	kilometre, kilometres, kilometer, kilometers	Multiply by 1000 or divide by 0.001
	mi	Mile	width=1.45 mi	mile, miles	Multiply by 1609.344 or divide by 0.000621371192
	nmi	Nautical Mile	distance=6 nmi	international nautical mile	Multiply by 1852
	<feet>'<inch>"	Feet and inches combined	maxwidth=12'5"	ft in	Multiply the feet by 12, add the inches and multiply the result by 0.0254
Speed	km/h	Kilometres per hour	minspeed=80 km/h	kph, kmph	-
	mph	Miles per hour	maxspeed=60 mph		Multiply by 1.609344
	knots	Knots	maxspeed=10 knots		Multiply by 1.852
Weight	t	Tonne (metric ton)	maxweight=3 t		-
	kg	Kilogram (kilogramme)	maxweight=3500 kg	-	Divide by 1000
	st	Short ton			Multiply by 0.9071847

Common mistakes

The following table presents examples of incorrect or discouraged tag usage together with their correct notation.

Incorrect usage	Explanation	Correct usage
height=6m	Missing space between numeric value and unit.	height=6 m
maxweight=3,5	Comma used as decimal separator.	maxweight=3.5
width=12' 6"	There should be no space between the specification of feet and inches.	width=12'6"
maxspeed=50 kph	Usage of an alias.	maxspeed=50 km/h

See also

• Category:Units for a list of related tags and pages
• Units of measurement on Wikipedia