try this conversion chart:
http://www.jewelrybynet.com/jbn_lc_body-jewelry-body-jewelry-conversion-chart.asp
..hope it helps. :)
4 millimeters is 0.4 centimeters. 1 cm is 10 millimeters.
There are 10 millimetres in one centimetre. Therefore, 4 millimetres is equal to 4/10 = 0.4 centimetres.
1 inch = 2.54 centimeters
40 millimeters are in 4 centimeters.
Multiply by 2.54 Answer 4 x 2.54 = 10.16 centimeters