The answer will depend on what aspect of the calculator you wish to measure: its length, volume, mass, weight, temperature, etc.
A microgram.
kilometre
Tonnes
I would say centimeters, not inches
It would be millimetres.
A calculator would be between 100 and 150 millimetres.
Millimetre.
Metres; centimetres are too small, kilometres are too large.
The weight of the box would be measured in grams.
Metres
A microgram.
Potatoes are sold by the kilogram.
a calculator
A thermometer.
distance
Centimeters
kilograms