PENNY-INCH NAIL EQUIVALENTS
2d = 1"
3d = 1-1/4"
4d = 1-1/2"
5d = 1-3/4"
6d = 2"
7d = 2-1/4"
8d = 2-1/2"
9d = 2-3/4"
10d = 3"
12d = 3-1/4"
16d = 3-1/2"
20d = 4"
30d = 4-1/2"
40d = 5"
50d = 5-1/2"
60d = 6"
70d = 7"
80d = 8"
Nail Gauge Decimal Equivalent (Inch)
Origin of "PENNY-WISE" Nail Designations
There are two explanations for the English "penny" system of designating nail lengths. One is that the eight penny, six penny, two penny nails, etc. were
so-called originally because one hundred nails cost eightpence, sixpence, twopence, etc. The other theory says that one thousand eight penny nails, for
example, weighed eight pounds, one thousand four penny nails weighed four pounds, etc.
The "d" abbreviation for penny (8d for example) is of ancient origin and represents the first letter of the Roman coin denarius.
Nails used for wood-to-wood applications (such as wood siding nails, cedar shingle nails, etc.) are traditionally referred to by the "penny" designation, i.e.,
5d or 6d nails, etc. However, nails for non-wood applications, fiber-cement siding nails, metal roofing nails, etc. are primarily referred to by inches, i.e., 1
1/2" or 2" nails, etc.
There is no readily apparent system for correlating the various penny designations. They must be memorized individually.
Adapting the tool to the situation
As technology has progressed, it has also created both the demand for and the means to produce nails that are more and more adapted to precise
situations. In other words, you wouldn’t use roofing nails to fasten crown moulding or finishing nails to frame a house, so be sure to choose the right
fastener to make the job easier and help assure its success. Thus, before buying nails, ask yourself the following:
Am I working indoors or out? If you’re outside, you may want to opt for galvanized or hot dipped galvanized, stainless steel or copper nails that present
varying levels of corrosion resistance and compatibility with the surfaces being fastened.
What type of materials am I working with? There are nails for fastening everything from drywall to wood, to masonry, to metal, etc.
Am I working with heavy or light materials? Why go to the expense of using heavy, and consequently more expensive fasteners, when light ones will do
the job. The opposite is also true; framing a house with undersized, but cheaper, nails is a recipe for disaster.
In Canada, nails are manufactured to imperial dimensions. Diameter is specified by gauge under British Imperial Standard. In the United States, nails are
designated by the term “penny” which refers to the number of nails of a certain length and diameter (gauge) in one pound. For example 12d (“d” is the
abbreviation for penny), 3 inch, no. 9 contains 60 nails in a pound, while 16d, 3-inch, no. 8 contains 45 nails in a pound.
Nails measure between ½ inch (13 mm) and 6 inches (150 mm). A nail measuring more than 6 inches is called a spike that can measure up to 14 inches
(350 mm). Spikes are almost always made of steel.
Nails are generally divided into interior and exterior categories. A few factors that determine nail types are corrosion resistance, fixation capacity, size,
Type Corrosion resistance Fixation capacity Sizes (in inches) Comments
Finishing Limited Limited 1 to 3 Small heads, for mouldings, casings, etc.
Roofing High Medium 3/4 to 2 1/2 Large heads, galvanized or aluminium, optional rubberized disc below head for waterproofing.
Masonry Limited High 3 to 5 1/2 Carbon steel, some with double heads for wood foundation forms, etc.
Common Limited Medium 1 to 6 Steel, general purpose, galvanized or not.
Box Limited Limited 1/2 to 3 Steel, general purpose, smaller jobs.
Spiral Varies High 1/2 to 6 Steel, galvanized or not.
Gutter spikes High High 6 or 7 To hold gutters.
Ringed Varies Very high 1/2 to 6 Highest fixation capacity.
Brad Limited Medium 1/2 to 3 Finishing and furniture nail, very thin shank and small head.
Gypsum Wallboard Limited High 1 1/8 to 2 Proportionately large flat head.
Flooring Limited Medium 2 Ideal for hardwood floors.
There are six main characteristics that distinguish nails:
Finishing nails have small indented heads and are mainly used for installing mouldings, door and window casings, in furniture, etc, when nail heads must
Flat countersink nail heads are designed to be hidden, so are generally used for indoor floors and mouldings when regular finishing nails won’t do.
Flat heads are considered to be the all-purpose nail head and used in all types of building.
Large flat heads are designed to resist tearing in such materials as shingles and construction paper.
Oval heads are decorative and seen in upholstering and some finishing.
Smooth shanks nails are the most common although they have the least holding power. Their large head and shank diameter make them easier to drive
Spiral (helical) shanks are next in line as to holding power. Their resistance to tearing out is 50% to 200% higher than the smooth variety.
Ringed shanks have the highest holding power. When using this type of shank, remember that they cannot be removed without causing damage to the
Cut flooring nail shanks are rectangular, tapered and the point is blunt to avoid splitting wood flooring.
Diamond points are the most common.
Blunt diamond used in harder wood to prevent splitting.
Long diamond points are sharper and penetrate more easily.
Duckbill points, although less common, have superior holding power.
Conical points are used in masonry nails. Present less friction than diamond points.
Aluminium nails are corrosion resistant and therefore indicated for outdoor use as roofing nails, for construction paper, etc.
Steel is the most common nail material, but it rusts easily and should only be used indoors.
Carbon steel nails are harder than regular steel nails, so more suitable for harder materials.
Stainless steel nails are suitable for outdoor use.
Copper nails are corrosion free and are the only material type that can be used when other copper materials such as eaves troughs, roof covering and
flashing are being installed.
Bright (normal finish) nails aren’t corrosion resistant, so recommended only for indoor use.
Blued nails are covered with a thin methyl oxide finish designed to help the nail hold more solidly. This type of nail is most often used in partitions and
lath. Not corrosion resistant.
Heat treating nails is a process to harden nails for use in hardwoods and concrete. Not corrosion resistant.
Galvanized zinc nails are electroplated to increase resistance to corrosion. This process does not entirely prevent corrosion so electroplated galvanized
nails should only be used indoors or in areas not directly exposed to the elements.
Hot-dip galvanized nails are dipped in a zinc alloy and are much more corrosion resistant. They can be used outdoors.
Paint is used as a decorative device and generally reserved for finishing nails to match wall and/or moulding and casing colours.
Vinyl and resin coatings on nails heat up from the friction of being driven into a surface and “glue” themselves into the host. This is particularly useful
when nailing green wood that’s subject to warping and twisting that can pull out non-coated nails. Vinyl coated nails hold more solidly. This coating is
employed primarily on nails used in mechanical nailers.
½ inch to 6-inches.
Use nails that are 2 1/2 to 3 times the thickness of the thinner of the two nailing surfaces. Always nail the thinner board into the thicker one.
About 175 years ago, a small band of British Isles immigrants settled along the banks of the Salmon Rive in Quebec’s
Eastern Townships. Their choice of location proved to be a mistake and for various reasons they were forced to
relocate upriver. Before leaving they decided to burn most the houses and buildings that they’d erected with so much
labour and sacrifice. Practical by necessity, they knew that burning was the most efficient way to recuperate the
precious metal nails…
Fortunately, times have changed and these days buying nails is no more complicated than making the short trip to the