1 année lumière(al) = 9460730472580.8 km;
1 unite astronomique(ua) = 149597870.700 km; (28ème Assemblée générale de l’Union astronomique internationale, tenue fin août 2012)
1 km = 1000 m;
1 cm = 0.01 m;
1 mm = 0.001 m;
1 μm = 10-6 m = 0.001 mm;
1 nm = 10-9 m = 0.001 μm;
1 angstrom = 10-10 m = 0.1 nm;
1 mille marin = 1852 m;
1 mille = 1609.344 m;
1 yard = 0.9144 m;
1 pied (foot) = 0.3048 m;
1 pouce (inch) = 0.0254 m;
Remarques