Why is a nail size called a penny, and why the symbol “d”? Packaging Incorporated – BlackHawk Packaging

Why is a Nail Size Called a Penny and Why Does it Have the Symbol “d”?

Why nail size is called a penny

By: Ben Anderson, Packaging Incorporated Sales Representative

The answer is of ancient origins…

Anybody who has been on a housing construction job site has likely heard the term 8 or 16 “d” (Dee) and/or 8 or 16 penny. This term is primarily used by carpenters referring to nails.

Why is a nail size called a “penny” in the first place, and what does it mean?

Most common nails used in wood to wood construction are referred to in “d” or penny terminology. The “d” is the symbol for penny, which can be traced back as far as the Ancient Roman Empire. There are two theories as to how exactly the measurement came into being. What is conclusive is that the “d” stands for the Roman coin denarius. In English it means “the penny.” The denarius was the coin which many a person used in the Roman empire during the time when Rome occupied what is now England. That’s why it’s called a penny but uses a “d” as the symbol. Now you know!

The origin of the “d” symbol on nails

The three theories as to how exactly it came into being are as follows:

  1. Six penny, eight penny, 12 penny nails, etc. were so called because one hundred hand-forged nails of a length cost sixpence (6 pennies), eightpence, twelvepence, etc.
    Example: 100  3-1/2” nails = 16 pennies, or denarius. To this day, 3-1/2” nails are 16d (penny) nails.
  2. The other is that one thousand eight penny nails weighed 8 pounds, but this doesn’t exactly explain the length.
  3. The final theory is the same as #1, except a single nail cost so many pennies, but it is unlikely that they were this expensive, even in ancient times.

In today’s world, terminology gets thrown out there all the time and is subject to interpretation. In talking with contractors, most of them will call a 3-1/4” strip framing nail a 16d and a 3” a 12d, though both are technically wrong. This is shown by the chart below.

However, most people don’t get caught up on the penny terminology anymore, and prefer to call a nail by its length. This is also shown in the fact that strip nails technically are not a true 8 penny nail, though every brand refers to them as 8d.

I found it fascinating to know where the terminology first originated and thought I would share.

See the chart below for a reference guide from penny to inch conversions.

Penny (d)= Inches
2d1”
3d1-1/4”
4d1-1/2”
5d1-3/4”
6d2”
7d2-1/4”
8d2-1/2”
9d2-3/4”
10d3”
12d3-1/4”
16d3-1/2”
20d4”
30d4-1/2”
40d5”
50d5-1/2”
60d6”
70d7”
80d8”
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