Nail length is given in “penny” sizes, written with a “d” (from the old British penny). This chart converts penny size to length with common uses.
| Penny size | Length | Common use |
|---|---|---|
| 2d | 1 in | Trim, small work |
| 4d | 1-1/2 in | Trim, lath |
| 6d | 2 in | Siding, trim |
| 8d | 2-1/2 in | Framing, subfloor |
| 10d | 3 in | Framing |
| 12d | 3-1/4 in | Framing |
| 16d | 3-1/2 in | Framing (most common) |
| 20d | 4 in | Heavy framing |
16d is the framing standard. For nailing 2x material together (like studs to plates), the 16d common nail is the workhorse. Use galvanized or stainless outdoors.
FAQ
Why do nail sizes use the penny (d) system? The penny system is a historical sizing convention where a higher number indicates a longer nail (like 16d being longer than 8d), rather than referring to diameter, cost, or weight directly, which is why nail size charts are needed to translate penny size into actual length.
See the Screw Size Chart and Fastener Size Chart.