You could use cm, meters (eg. 0.18cm ) or millimetres . A mix of cm and mm should be best for accuracy .
Kilometres
Metric system: meters; customary system: feet
Length, width and height are all measurements of distance. Distance is measured in meters (metric system) or inches/feet/miles (imperial system).
Yards if you work in imperial units or metres if you work in metric units
You could measure with Kilometers, Deckameters,hectometers,meters,decimeters,centimeters,millimeters, or micrometers. To give you an idea, one centimeter is equal to 2.54 inches. There are about three feet in one meter.
The width of an adult's hand is typically around 8-9 centimeters in the metric system.
the metric system
cm
Width is a length or distance. The unit of length is the meter.
centimetre
A millimetre.
Kilometres
It would be millimetres.
Metres, to measure its length or width, square metres to measure its area.
The metric unit used for measuring the width of a fingernail is usually millimeters (mm).
The width of a pin would typically be measured in millimeters (mm).
Millimetres (or centimetres to one decimal place).