How do you convert a measurement in millimeters to kilometers?

1 millimetre = 0.000001 kilometres.

Start with 1 mm. There are 10 millimetres to a centimetre, so divide 1 by 10. Answer is 0.1 cm. There are 100 centimetres in a metre, so divide answer by 100. Answer is 0.001 m. There are 1000 metres in a kilometre, so divide last answer by 1000. Answer is 0.000001 km.