Metres or square metres - depending on whether you wanted to measure its linear dimensions or its floor-space (area).
A metre would be an appropriate unit.
The meter.
a kilmoeter
Meter
Dm
mm
Metres, to measure its length or width, square metres to measure its area.
None! I would measure in centimeters if I were you!
Milimeter
Most like a vernier caliper for accurate readings
I would go with millimetres
mm
centimetre
cm
It would be millimetres.
Kilometres
Metres, to measure its length or width, square metres to measure its area.
None! I would measure in centimeters if I were you!
a yard stick
meters
Milimeter
Most like a vernier caliper for accurate readings