Nail size chart by penny
What each penny size actually measures, the shank diameter in all three families, and how many come to the pound. The classic wall chart, with the column that says where the penny formula stops being true.
| Size | Length | Common | Box | Finish | Commons per lb | Penny rule |
|---|---|---|---|---|---|---|
| 2d | 1" | 0.072" | 0.072" | 0.062" | 868 | holds |
| 3d | 1 1/4" | 0.08" | 0.076" | 0.067" | 562 | holds |
| 4d | 1 1/2" | 0.098" | 0.08" | 0.072" | 312 | holds |
| 5d | 1 3/4" | 0.098" | 0.086" | 0.072" | 268 | holds |
| 6d | 2" | 0.113" | 0.099" | 0.092" | 176 | holds |
| 7d | 2 1/4" | 0.113" | 0.099" | 0.092" | 157 | holds |
| 8d | 2 1/2" | 0.131" | 0.113" | 0.098" | 105 | holds |
| 10d | 3" | 0.148" | 0.128" | 0.113" | 68 | holds |
| 12d | 3 1/4" | 0.148" | 0.128" | 0.113" | 63 | says 3 1/2" |
| 16d | 3 1/2" | 0.162" | 0.135" | 0.135" | 49 | says 4 1/2" |
| 20d | 4" | 0.192" | 0.148" | not made | 31 | says 5 1/2" |
| 30d | 4 1/2" | 0.207" | 0.148" | not made | 23 | says 8" |
| 40d | 5" | 0.225" | 0.162" | not made | 18 | says 10 1/2" |
| 60d | 6" | 0.263" | not made | not made | 11 | says 15 1/2" |
Reading it
- The penny rule is length = penny ÷ 4 + 1/2". It is exact from 2d to 10d and then breaks — the last column says so at every size where it does, and above 10d the table is the authority.
- Diameters are the ASTM F1667 figures. A box nail is the same length on a thinner wire, which holds less and splits less; a finish nail is thinner again and is trim only, never structural.
- A nailing schedule that calls for commons is assuming that diameter. Substituting box nails of the same length quietly reduces the connection.
- The per-pound count is the volume of the shank times the density of steel, which lands on the published counts because the head and the point roughly cancel. Real boxes vary by maker, and hot-dipped galvanised nails carry measurable zinc.
Sources: ASTM F1667, Standard Specification for Driven Fasteners: Nails, Spikes, and Staples, ASTM International.
For the case this table does not cover
- Nail sizes
What a 16d actually measures, common against box against finish, and how many come in a pound.
- Fastener calculator
Screws or nails for a sheet good on an edge-and-field pattern, with the box count to buy.
The tool this table is for
- Nailer
Penny sizes, gauges, and how many nails a sheet of subfloor actually takes.