Nail & Screw Size Chart (Penny Sizes, Gauges & Uses)
Part of Decks, Fences & Roofing
Quick answer
Nails are sized by the penny system (d): a 16d nail is 3½ inches, an 8d is 2½ inches. Screws are sized by gauge (#) for diameter and inches for length — a #8 screw is about 0.164 inch across. Match the fastener length to roughly 2–3× the thickness of the material you're fastening through.
Fasteners come in two sizing systems: nails use the old "penny" scale (written with a d), and screws use a gauge number for thickness plus a length in inches. These tables cover the common sizes and what each is for.
Nail size chart (penny to length)
| Penny size | Length | Typical use |
|---|---|---|
| 2d | 1" | Trim, small finish work |
| 3d | 1¼" | Trim, lath |
| 4d | 1½" | Trim, shingles |
| 6d | 2" | Siding, fencing, trim |
| 8d | 2½" | Subfloor, sheathing, toe-nailing |
| 10d | 3" | Framing |
| 12d | 3¼" | Framing |
| 16d | 3½" | Framing — the standard for 2× lumber |
| 20d | 4" | Heavy framing |
Wood screw gauge chart (gauge to diameter)
| Gauge | Diameter | Typical use |
|---|---|---|
| #4 | 0.112" | Small trim, hardware |
| #6 | 0.138" | Cabinet, light trim |
| #8 | 0.164" | Decking, general construction |
| #10 | 0.190" | Decking, ledger, heavy hardware |
| #12 | 0.216" | Heavy structural |
| ¼" | 0.250" | Lag / structural screws |
What size fastener for the job
| Job | Fastener |
|---|---|
| Framing 2× lumber | 16d (3½") nails or 3" structural screws |
| Subfloor to joists | 8d ring-shank nails or 2½"–3" subfloor screws |
| Wall sheathing | 8d (2½") nails |
| Decking boards | 2½"–3" (#8–#10) deck screws |
| Drywall to studs (½") | 1¼" coarse-thread drywall screws |
| Trim & molding | 4d–6d finish nails or 1½"–2" finish screws |
Rule of thumb: a fastener should penetrate the base material by about twice the thickness of the piece you're attaching (and at least an inch into framing). Use ring-shank or coated screws/nails outdoors, and stainless or hot-dip galvanized with cedar and treated lumber to avoid corrosion stains.
FAQs
What size nail is 16d?
A 16d ("16-penny") nail is 3½ inches long — the standard for framing 2× lumber. The "d" is the historical penny abbreviation.
What does screw gauge mean?
Gauge is the screw's shank diameter — the higher the number, the thicker the screw. A #8 screw is about 0.164 inch across; a #10 is 0.190 inch. Length is given separately in inches.
What screws should I use for decking?
Use 2½ to 3 inch #8–#10 deck screws, coated or stainless for corrosion resistance. The screw should reach well into the joist below the board.