ruler
miles or kilomiters
feet
miles
A metres, for an approximate measure, a centimetre for a more accurate measure.
Millimeters
ruler
Mm
By unit of length and distance and conversion ,we can say that a finger nail is measured with millimeters.
The metric unit used for measuring the width of a fingernail is usually millimeters (mm).
Millimetres.
The estimating unit of measure for the width of a fingernail is typically in millimeters (mm) or centimeters (cm). Some may also use inches (in) as a measurement unit, but millimeters are the most commonly used unit for the width of a fingernail.
By unit of length and distance and conversion ,we can say that the most appropriate unit to measure the length of a finger is cm.
Inches
cm
I would use feet
You would use meters.