Nail Size Chart
There are dozens of different types of nails used for different jobs. And within each type there are a wide variety of sizes. Look at fig.1 to see how nails are measured and to learn some of the lingo so you’ll sound like a pro when you go to the hardware store.
Different Nail Sizes:
This system originated in 15th century England, when the "penny" size determined what one paid a blacksmith to forge a hundred nails of that size of nail (one paid three pennies to get a hundred nails of the size called the "3-penny" nail). This price became obsolete before 1500, but has continued to be so entrenched in convention, that its use persists to this day. Now we use it primarily as a measure of length (approximate, at least). We abbreviate the "penny" with the symbol "d", which came from the "denarius", an early Roman coin.
(Used by permission from www.sizes.com)