Ever stood in the hardware aisle at 7:00 AM, staring at a box of nails labeled "16d" and wondered what on earth the letter 'd' has to do with a piece of steel? It's confusing. Honestly, it’s one of those weird holdovers from history that makes zero sense until someone actually explains the backstory. You’re looking for a nail penny size chart because you probably just want to know if that 3-inch sinker is actually going to hold your 2x4s together or if it's going to poke through the other side of your project.
The "d" actually stands for "denarius." That’s an old Roman coin. Back in 15th-century England, nails were sold by the hundred. If 100 nails cost eight pence, they were called eight-penny nails. Simple, right? Except now we don't buy nails by the hundred at the local blacksmith, but the names stuck like glue.
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Decoding the Nail Penny Size Chart
If you’re trying to visualize this, just remember that as the "d" number goes up, the nail gets longer. A 2d nail is tiny—about an inch. A 60d nail? That’s basically a spike. It’s six inches of terrifying metal. Most DIYers spend their lives in the 6d to 16d range.
Let's break down the common lengths you'll actually use. A 2d nail is exactly 1 inch long. Every step up in the "penny" count generally adds a quarter-inch, but only until you hit a certain point. It’s not a perfectly linear math equation because, well, history is messy. For instance, a 3d nail is 1.25 inches. A 4d nail is 1.5 inches.
Then things get a bit wonky.
Once you get to a 10d nail, it’s 3 inches long. But a 12d is 3.25 inches. If you’re building a deck or framing a shed, the 16d nail is your best friend. It’s 3.5 inches long. This is the industry standard for framing because it’s long enough to bite deep into a stud but not so long that it’s impossible to drive in without a pneumatic nailer.
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Why Does the Gauge Matter Too?
Length isn't the only thing. You’ve also got to think about thickness, or the "gauge."
A box of nails might say "16d Common" or "16d Sinker." They are the same length, but they aren't the same nail. A common nail has a thicker shank. It’s tough. You use it for heavy-duty framing. A sinker is slightly thinner and usually has a vinyl coating. That coating creates friction when you hammer it in, which melts the vinyl and basically glues the nail into the wood. It also makes it slide in easier. If you’ve ever tried to hand-drive a common 16d into a piece of kiln-dried douglas fir, you know why sinkers were invented. Your forearm will thank you.
Box nails are another variation. They’re even thinner than common nails. Use these if you’re worried about splitting the wood. If you use a thick common nail on a thin piece of trim, crack. Project ruined.
Quick Reference for Common Projects
- Birdhouses or thin crafts: Use 2d (1") or 3d (1.25") nails.
- Interior trim and baseboards: Usually 4d (1.5") to 6d (2").
- General construction/fences: 8d (2.5") is the sweet spot.
- Wall framing (studs): 16d (3.5") is the king here.
The Mystery of the Shorter Penny Sizes
Why do we even have half-inch increments sometimes? It comes down to the thickness of the lumber. Standard "2x" lumber (like a 2x4) is actually only 1.5 inches thick. If you are nailing two 2x4s together flat, you need a nail that passes through the first one and deep into the second without coming out the other side.
A 10d nail is 3 inches. That is exactly the thickness of two 2x4s stacked together. If you use a 12d (3.25"), the tip is going to snag your shirt every time you walk past it.
Material Matters
You also can't just grab any 8d nail and head outside. If you're using pressure-treated wood—the green-tinted stuff used for decks—you need hot-dipped galvanized nails. The chemicals in treated wood eat through regular steel like acid. Within a few years, your shiny "bright" nails will turn into streaks of rust and your deck will literally fall apart.
Stainless steel is even better if you live near the coast. Salt air is brutal. It’s more expensive, but so is rebuilding a porch.
Getting the Most Out of Your Hardware
Don't just look at the nail penny size chart and pick the longest one "just to be safe." Over-nailing is a real thing. If you put too many thick nails in a row, you're essentially creating a perforated line in the wood. One good gust of wind or a heavy load, and the wood splits right along that line.
Spacing matters. Depth matters.
And for the love of all things holy, learn to blunt the tip of your nail if you're working with wood that splits easily. Just tap the sharp point of the nail with your hammer to flatten it slightly before you drive it in. Instead of acting like a wedge that pries the wood fibers apart, a blunt nail punches through the fibers. It's a weird old-school carpenter trick that actually works.
Beyond the Penny: The Metric Shift
Most of the world uses millimeters. Even in the US, if you buy power nailer "strips" for a Paslode or DeWalt gun, the box will often list the length in inches (like 3-1/2") alongside the penny size. The industry is slowly moving away from the "d" designation because, frankly, it's confusing for new builders.
But if you’re reading a set of blueprints from an architect or a DIY plan from a magazine, you’re going to see "10d" and "16d." You have to know the language. It’s like learning to speak "contractor."
Summary Table of Lengths (The "Cheat Sheet")
2d: 1 inch
3d: 1-1/4 inches
4d: 1-1/2 inches
5d: 1-3/4 inches
6d: 2 inches
7d: 2-1/4 inches
8d: 2-1/2 inches
9d: 2-3/4 inches
10d: 3 inches
12d: 3-1/4 inches
16d: 3-1/2 inches
20d: 4 inches
30d: 4-1/2 inches
40d: 5 inches
50d: 5-1/2 inches
60d: 6 inches
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Practical Next Steps
Before you start your next build, check your lumber thickness. If you’re joining two pieces of wood, ensure the nail is long enough to penetrate the second piece by at least 1 inch, but short enough to stay hidden. Grab a box of 8d hot-dipped galvanized nails for any outdoor fence repairs, and keep a box of 16d sinkers for any heavy framing. If you're doing delicate indoor molding, skip the penny sizes altogether and look for 18-gauge brad nails, which are measured strictly by inches. Matching the right "d" to your lumber thickness is the easiest way to ensure your project doesn't just look good, but actually stays together for the next twenty years. Scan your local hardware store's "bulk" bins—they usually have the penny sizes marked clearly on the scales, which is a great way to get a feel for the different weights and thicknesses before buying a 50-pound box.