Refer to this for nail lengths. The letter d, the first letter of denarius (a Roman coin), stands for “penny.” A 2d equals 1 inch, 3d=1-1/4 inches, 4d=1-1/2 inches, 5d=1-3/4 inches, 6d=2 inches, 10d=3 inches, 20d=4 inches, and 40d=5inches.
By Yankee Magazine
Mar 24 2013