Haugh unit

The Haugh unit is a measure of the internal quality of an egg. An egg is weighed, then broken onto a flat surface (breakout method), and a micrometer used to determine the height of the thick albumen (egg white) that immediately surrounds the yolk. The height, correlated with the weight, determines the Haugh unit, or HU, rating. The higher the number, the better the quality of the egg (fresher, higher quality eggs have thicker whites). The test was introduced by Raymond Haugh in 1937, and is considered the most significant measure of egg quality.

Formula [http://www.pjbs.org/ijps/fin76.pdf]

HU = 100 log(h-.01*5.6745(30w^.37-100)+1.9)

Where
*HU = Haugh unit
*"h" = observed height of the albumen in millimeters
*"w" = weight of egg in grams