How far is a hairbreadth away?

Answer 1

Figuratively, this is an extremely short or small distance, as in, "She won the race by a hairbreadth".

Literally, human hairs will vary in thickness, but most measurements range in breadth (width) between 50 microns for very fine hair to 100 microns for coarse hair.

The word hairbreadth, or hairsbreadth, was first used this way, to indicate a distance so small it could almost be compared to the small size of the diameter, or width, of a human hair, sometime around the mid 18th century.