Inch
Symbol: in
The origin of the inch is disputed. Historically, in different parts of the world (even different cities within the same country) and at different points in time, the inch has referred to similar but different standard lengths.
The English word inch comes from Latin uncia meaning "one twelfth part" (in this case, one twelfth of a foot).
Effective July 1, 1959, the United States and countries of the British Commonwealth defined the length of the international yard to be exactly 0.9144 meters. Consequently, the international inch is defined to be equal to exactly 25.4 millimeters.
1in = 0.0254m
1m = 39.3701in