In the
United States
The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...
, the length of a
nail is designated by its penny size, written with a number and the abbreviation ''d'' for penny; for example, ''10d'' for a ten-penny nail. A larger number indicates a longer nail, shown in the table below. Diameter of the nail also varies based on penny size, depending on nail type. Nails under inch, often called brads, are sold mostly in small packages with only a length designation or with length and
wire gauge
Wire gauge is a measurement of wire diameter. This determines the amount of electric current the wire can safely carry, as well as its electrical resistance and weight.
Types of wire gauge
Wire gauges may be broadly divided into two groups, t ...
designations; for example, ''1″ 18 ga.'' or ''″ 16 ga.''
Penny sizes originally referred to the price for a hundred (100) or
long hundred
The long hundred, also known as the great hundred or twelfty, is the number 120 (in base-10 Hindu-Arabic numerals) that was referred to as ''hund,'' ''hund-teontig,'' ''hundrað'', ''hundrath'', or ''hundred'' in Germanic languages prior to the ...
(120) nails in
England
England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...
in the 15th century: the larger the nail, the higher the cost per long hundred. The system remained in use in England into the 20th century, but is obsolete there today. Nails are still designated in penny sizes in the United States.
In Canada, nails are specified by the type and length and are still manufactured to Imperial dimensions. Nail diameter is specified by gauge number (British Imperial Standard). The gauge is the same as the wire diameter used in the manufacture of the nail.
The ''d'' is an abbreviation for ''
denarius
The ''denarius'' (; : ''dēnāriī'', ) was the standard Ancient Rome, Roman silver coin from its introduction in the Second Punic War to the reign of Gordian III (AD 238–244), when it was gradually replaced by the ''antoninianus''. It cont ...
'', a Roman coin similar to a
penny
A penny is a coin (: pennies) or a unit of currency (: pence) in various countries. Borrowed from the Carolingian denarius (hence its former abbreviation d.), it is usually the smallest denomination within a currency system. At present, it is ...
; this was the abbreviation for the
monetary penny in the
United Kingdom
The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...
before decimalisation.
{, class="wikitable" style="text-align: right"
! Penny size !! Length
(inches) !! Length
(nearest mm)
, -
, 2d , ,
, -
, 3d , ,
, -
, 4d , ,
, -
, 5d , ,
, -
, 6d , ,
, -
, 7d , ,
, -
, 8d , ,
, -
, 9d , ,
, -
, 10d , ,
, -
, 12d , ,
, -
, 16d , ,
, -
, 20d , ,
, -
, 30d , ,
, -
, 40d , ,
, -
, 50d , ,
, -
, 60d , , {{convert, 6, in, 0, disp=table
References
Obsolete units of measurement
Units of length
Nail (fastener)