Nail size chart — the penny system from 2d to 60d

Because the size originally quoted the price of a hundred of them in fifteenth-century England, where a hundred tenpenny nails cost ten pence. The abbreviation is a 'd' rather than a 'p' because the English penny was the Roman denarius, and 'd' stayed the symbol for it right up to decimalization in 1971. A competing account has the number describing the weight of a thousand nails instead; either way, the price relationship stopped meaning anything centuries ago and the label survived as a pure size code.

Three and a half inches, if it is a 16d common or a 16d box. A 16d sinker is 3 1/4 in — the coated framing nail sold in bulk buckets is a quarter inch shorter than the size on the label, and it shares that length with the 12d sinker. This matters when a plan calls for penetration into the receiving member, which is measured from the far face of the piece being fastened rather than from the head.

No, not without approval. At the same penny size a box nail is one to two wire gauges thinner — 0.135 in against 0.162 in at 16d — and the lateral design value in the code tables is driven by that diameter, so substituting downward quietly reduces the connection's rated capacity. The substitution runs the other way as well: a common nail where a box was specified splits thin material that the thinner shank would have survived.

Loosely, and the gap is the source of most of the confusion on a framing site. Collated strips and coils are specified as a length and a diameter — 3 1/4 in × 0.131 in, say — and then marketed as '16d' because they are used where 16d commons would be. That nail is 3 1/4 in long with a 10 1/4 gauge shank, which is the diameter of an 8d common: same length as a sinker, thinner than a 16d, and legal or not depending entirely on what your inspector accepts against the fastening schedule.

About 2,440 if they are 16d commons and roughly 5,230 if they are 8d, and this page calculates the figure rather than copying it: shank volume multiplied by the density of steel comes within about three percent of every published bright common count, because the extra metal in the head and the metal missing from the point taper nearly cancel. Coatings break that agreement — hot-dip galvanizing adds enough weight to take a noticeable slice off the count, and vinyl-coated sinkers land somewhere between.

Hot-dip galvanized to ASTM A153 or stainless, and nothing else outdoors. The copper-based preservatives that replaced CCA are considerably more corrosive to bare and electroplated steel, and an electroplated nail in a treated ledger can lose its coating in a few seasons — the failure shows up as rust streaks on the face long before the fastener is actually gone. Stainless is the answer near salt water and under cedar and redwood, whose own tannins attack zinc.

8d common at 6 in on the panel edges and 12 in in the field for anything 19/32 in and up, dropping to 6d for 3/8 to 1/2 in wall sheathing. The edge spacing is the number that gets missed: a panel nailed at 12 in all over has roughly half the shear capacity the schedule assumes, and it is invisible once the siding goes on. Shear wall details on an engineered plan tighten the edge nailing further, sometimes to 3 in, and that detail beats the general table.