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
One centimeter (cm) is a unit of length in the metric system, equal to one one-hundredth of a meter. It is commonly used to measure shorter distances and dimensions, such as height or width. To put it in perspective, a centimeter is roughly the width of a large paperclip.
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
the answer is ? it is so unknown
the metric system
cm
To measure a sharpener in the metric system, you would typically use centimeters (cm) for its length, width, and height. If you need to measure smaller dimensions, millimeters (mm) might be more appropriate. For weight, grams (g) would be used.
Width is a length or distance. The unit of length is the meter.
It would be millimetres.
centimetre
A millimetre.
Kilometres
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).