The "millimeter" would be perfect.
A metre.
Inches
cm
The ISO length unit to use would be the cementer.
I would use feet
You would use meters.
always the meter to measure length. This is an SI (international) unit of measurment, and is the standard international unit of measurment for length.
a cm
Kilometers are a unit of length, used to measure distance.
miles or kilomiters
inch
A metres, for an approximate measure, a centimetre for a more accurate measure.