A centimetre, unless I wanted a very precise value (why?) in which case I would use a millimetre.
The metric unit of length is the 'meter'.
Millimetre.
Milimeters
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.
Length->metersVolume->LitersMass->grams
The metric unit of length is the 'meter'.
The basic metric unit of measure for length is the meter (m).
I would use centimetres.
feet
mmeters
Centimetres
centimeter
Millimetre.
Milimeters
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.
You would use a ruler and measure in millimeters or centimeters.
Length->metersVolume->LitersMass->grams