A 8d finish nail is 2.5 inches long. The ‘d’ in nail sizes like 8d refers to the penny size. Originally, nail sizes were determined by how many pennies per hundred nails they cost. An 8d nail would have cost 8 pennies per hundred nails. While the penny pricing system is no longer used, the sizing convention remains.
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The Penny Sizing System for Nails
The penny sizing system for nails has been in use for over 200 years. It originated in late 18th century England as a way for nail manufacturers to price their nails. At the time, larger nails were more expensive to make as they required more metal. Pricing nails by the penny allowed for an easy way to account for this size difference.
Under the penny system, the ‘d’ stands for penny and the number indicates cost per hundred nails. So an 8d nail would have cost 8 pennies per hundred nails. A 16d nail would have cost 16 pennies per hundred, and so on. The larger the nail, the higher the cost per hundred.
While manufacturers no longer price nails by the penny, the sizing system persists as a convenient way to designate nail sizes. It has the advantage of correlating nail size with an intuitive numbering system – higher numbers denote bigger nails.
Penny Sizes vs. Nail Lengths
The relationship between penny size and nail length is approximate. There is no exact standard. However, the penny size gives a good indication of the nail length to expect. Here are some common penny sizes and their corresponding lengths:
| Penny Size | Approximate Length |
|---|---|
| 2d | 1 inch |
| 4d | 1 1/4 inches |
| 6d | 2 inches |
| 8d | 2 1/2 inches |
| 10d | 3 inches |
| 12d | 3 1/4 inches |
| 16d | 3 1/2 inches |
As you can see, the nail length increases as the penny size goes up. However, the exact length can vary a bit based on the manufacturer. The penny size just provides a ballpark figure for nail length.
The Relevance of Penny Sizing Today
While no longer used for pricing, the penny system remains the dominant way nails are sized and labeled. Most nails sold today will have the penny size on their packaging or listed in their product descriptions. It’s a standard that allows easy communication of approximate nail sizes between manufacturers, suppliers, and consumers.
Retailers don’t have to list exact inch measurements for each and every nail they sell. And consumers can quickly get an idea of a nail’s length based on the penny size. Someone building a deck can purchase a box of 16d nails and know they will be getting 3 1/2 inch nails without having to check the fine print.
The penny sizing system also allows easy substitution between nail sizes for construction projects. If plans call for 8d nails but 10d nails are all that’s available, a builder can easily switch without recalculating measurements.
So while no longer used for pricing nails, the penny system persists as a convenient shorthand for nail sizes. Most other systems would require reference charts to convert sizes. The penny system builds the size approximation right into the label.
Penny Sizes for Other Fasteners
The penny system is sometimes used to designate lengths of other fasteners besides nails:
Screws
Many wood and drywall screws are sized using a penny designation. So an 8d screw would be around 2 1/2 inches, just like an 8d nail. However, not all screw manufacturers follow this convention.
Staples
Some staple packagings use penny sizes, especially heavy duty staples used in construction and pallet assembly. An 8d staple will be around 2 1/2 inches, like an 8d nail.
Brads
Brads are small, thin nails used for light duty fastening. Some brad packages use the penny size system. So an 8d brad would be around 2 1/2 inches long.
However, for many specialty fastener types like screws, staples and brads, the penny system is not as standardized across manufacturers as it is for common nails. Not all will follow the sizing convention and may use another length designation instead.
The Benefits of Familiarity with Penny Sizing
For DIYers, builders, and anyone who works with nails, familiarity with the penny sizing system is very beneficial:
- Allows quick identification of nail sizes from packaging labels
- Aids in selecting the proper nail for applications
- Allows easy substitution with different nail sizes
- Saves time otherwise spent looking up size conversion charts
Knowing the penny system well can make many construction tasks quicker and easier. You don’t have to worry about consulting size guides or whipping out a tape measure. The penny size contains all the essential length information right in its label.
The Bottom Line – What Size is an 8d Nail?
An 8d nail is approximately 2 1/2 inches long. The “d” in nail penny sizes is a legacy term meaning pennies per hundred nails. While no longer used for nail pricing, the penny designation remains a standard way of labeling nail lengths. Knowing the penny system well is a valuable skill for anyone who works with nails regularly.
So in summary, an 8d nail is the go-to nail size for manyfinish nailing tasks. Its 2 1/2 inch length provides holding power without being overly large and unsightly. Next time you see 8d on a nail package, you can confidently know you’re getting roughly 2 1/2 inch nails. Understanding penny nail sizes makes projects requiring nails much quicker and easier!