A measure of the size of nails, at least as early as the fifteeenth century – 21st century. Symbol, d. The symbol comes from the Latin denarius through the French denier, and is also the symbol for the monetary penny. There are 240 pennies to the pound sterling.

In current usage in the United States, a 2d nail is 1 inch long. Each 1d increase is ¼ inch increase in length up to 10d followed by a 12d which is 3¼″ long. A sixteen-penny nail is a ¼ inch longer than 12d, and the remaining sizes, beginning with 20d, are multiples of 10 and are each ½ inch longer than the preceding size.

illustration of nail lengths

In England before about 1488 the penny size was the price in pennies of 100 nails of that size. The hundred was the great hundred, 120, not 100. However, the penny system had already become purely conventional before Queen Elizabeth's time, because we find in merchants' books entries like 100 4d nails for 3 pence, 300 3d nails for 7½ pence, and so on. “By 1573 'sixpenny nail' sold in fact for 3½d per hundred.”

The size is not based on the nail’s weight in pennyweights.

Another incorrect theory sometimes met with² is that the pound was once abbreviated “d” and the “d” size of a nail was the weight in pounds of 1000 nails; that is, a thousand 2d nails would weigh 2 pounds. Confusion between “d” for penny and “d” for pound did the rest. R. E. Zupko, who made an extensive study of records of British weights and measures, makes no mention of “d” as an abbreviation for the pound.

1. Alison Hanham.
The Celys and their World. An English Merchant Family of the fifteenth century.
Cambridge (UK): Cambridge University Press, 2008.

Page 331.

2. American Electrician's Handbook, 12th ed.

Page 4-185.



ffor ii c of vi peny nayle     xijd

ffor a c of v peny nayle       vd.

ffor ii c of iiij peny nayle    viiid.

For two hundreds of six-penny nails, 12 pence.

For a hundred of five-penny nails, 5 pence.

For two hundreds of four-penny nails, 8 pence.

Henry Littlehales, transcriber and editor.
The Medieval Records of a London City Church (St. Mary at Hill) A.D. 1420-1559.
Original series nos. 125 and 128.
London: Published for the Early English Text Society by K. Paul, Trench, Trubner & Co., 1904-1905.

The quotation is from the records for 1477 of a church in London. A note in the Index (page 432) of the volume reprinting these records explains:

Dr. Murray points out that these Records completely explain the term “tenpenny” nail. The price of nails was expressed in their cost per hundred: twopenny nails originally cost twopence per hundred, pp. 69, 73, 101; threepenny nails threepence, 73, 82, 120, 138; fourpenny nails fourpence, 84, 87, 120, 138; fivepenny nails fivepence, 84, 88, 135;.sixpenny nails sixpence, 67, 82, 87, 138; and so with tenpenny nails, 67, 69, 72. These prices were retained until 1487-8, p. 138: after that date, however, the price dropped one penny per hundred, but the old designations were still used. Sixpenny nails were sold for fivepence per hundred, 151, 176, 281; fivepenny nails fourpence, 173, 175, 210, 281; fourpenny nails for threepence, 176, 351; threepenny nails for twopence, 281, 340, 351; threepence was charged for two-hundred twopenny nails, 281; and tenpenny nails appear, on one occasion, to have been bought at eightpence per hundred, p. 176. Entries which apparently signify recurrence to original prices occur at pp. 165, 176, 229, 248.


Nayles called grett naylles that ys to saye iiii d. naylle v d. naylles and vi d. naylles the b...xl s.

Nails called great nails, that is to say 4 penny nails, 5 penny nails and 6 penny nails, the barrel.....40 shillings. [customs duty]

From a 1702 copy (British Museum Add. Roll, 16577) of a manuscript internally dated 15 July 1507, consisting of a list of customs duties on various articles, as reproduced as Appendix C in Norman Scott Brien Gras, The Early English Customs System, Cambridge (MA): Harvard University Press, 1918, page 701.