From: http://en.wikipedia.org/wiki/Nail_%28engineering%29
Nail sizes
Nails are usually sold by the pound (either in bulk or in boxes). In the United States of America, the length of a nail is designated by its penny size. It is believed that the origin of the term "penny" in relation to nail size is based on the old custom in England of selling nails by the hundred. A hundred nails that sold for sixpence were "six penny" nails. The larger the nail, the more a hundred nails would cost. Thus the larger nails have a larger number for its penny size. The penny size is written with a number and the abbreviation d for penny (e.g. - 10d). D is an abbreviation for denarius, a Roman coin similar to a penny; this was the abbreviation for a penny in the UK before decimalisation. A smaller number indicates a shorter nail and a larger number indicates a longer nail. Nails under 1-1/4 in., often called brads, are sold mostly in small packages with only a length designation (e.g. 1/2", 1-1/8", etc.).
In other English-speaking countries, including Canada, nails are designated by type and length (not by penny).
Length of Nails by Penny Size
- 3d - 1-1/4"
- 4d - 1-1/2
- 6d - 2"
- 8d - 2-1/2"
- 10d - 3"
- 12d - 3-1/4"
- 16d - 3-1/2"
- 20d - 4"
- 40d - 5"
- 60d - 6"
----- Original Message -----
> November 2004 issue of WOOD Magazine. It has some interesting info,
> but I question its accuracy, in part because the last paragraph
> makes no sense at all if you do the calculations. (If the last
> number is a typo (should be 5") and the 16d to 20d is considered a
> "1d" increment, then it makes sense, but certainly the way it is
> written leaves a lot to be desired.)
> Anyone have better info?
>
> How are wood nails classified in metric countries? Simply by style
> and length?
> Jim Elwell
>
> ***************
>
> Q: What is the origin of "penny," the word used to define nail sizes?
>
> A: The "d" abbreviation for penny dates back to Roman times and the
> coin called the denarius. The "penny" system of nail designations,
> however, stems from the English pence. At no time did a 6d nail cost
> sixpence, but records showthat 100 6d nails had once cost that
> amount, and that 100 8d nails had simultaneously cost eightpence.
> Today, the "d" designation pertains more to length than cost. A 2d
> nail used with wood measures 1" long. Each 1d increment equals a
> 1/4" nail-length increase up to 16d. Above 16d, nail length
> increases come in 1/2" increments. that explains why a 10d nail is
> 3", and a 20d nail, the next size jump above 16d, measures 4".
> ***************
>
>
