Hair widths to survey feet equation
To convert hair widths to survey feet:
Multiply the number of hair widths by 0.5783321948841308
About hair widths
A human hair's width varies between 17 and 181 micrometers. The measurement used here is 144th of an inch — around 176 micrometers — it was sometimes used with English units, but is not included in the Imperial system.
About survey feet
One foot is 0.999998 the size of a survey foot.