Fasteners · Reference

Nail & screw size chart

Look up any penny (d) nail size in inches or millimetres, or any US wood-screw gauge, with the length, diameter, and the framing job each one is for. A 16d nail is 3-1/2 in long; a #8 screw is 0.164 in across.

Detail A — Size lookup

Nail dimensions

— Length

Length—

Shank diameter—

Common use—

01 How the chart works

There is nothing to calculate — both values are lookups, read from a table fixed by standards, not derived from the size name. The two systems work in opposite directions, which is the part that trips people up.

A nail's penny size (written 16d, the d is the old abbreviation for penny) sets its length. The step is a quarter-inch per size up to 12d, then a half-inch per size above that. A screw's gauge (written #8) sets its diameter; the length is a separate number stamped on the box, which is why a screw is called out as #8 × 2-1/2 in.

Nail penny size → fixed LENGTH (diameter varies by nail type)
Screw gauge → nominal DIAMETER ≈ 0.060 + 0.013 × gauge (in), length stated separately

The penny number is historical — it once meant the price per hundred nails — and it carries no arithmetic that gives you the diameter. That is the one piece of the chart every supplier agrees is not an equation.

Common nail sizes (bright, smooth shank), both units — length from the standard penny chart, diameter the ASTM F1667 / Maze Nails common-nail figure:

2d1 in · 25 mm — 0.072 in dia

3d1-1/4 in · 32 mm — 0.083 in dia

4d1-1/2 in · 38 mm — 0.102 in dia

5d1-3/4 in · 44 mm — 0.102 in dia

6d2 in · 51 mm — 0.113 in dia

7d2-1/4 in · 57 mm — 0.113 in dia

8d2-1/2 in · 64 mm — 0.131 in dia

9d2-3/4 in · 70 mm — 0.131 in dia

10d3 in · 76 mm — 0.148 in dia

12d3-1/4 in · 83 mm — 0.148 in dia

16d3-1/2 in · 89 mm — 0.162 in dia

20d4 in · 102 mm — 0.192 in dia

30d4-1/2 in · 114 mm — 0.207 in dia

40d5 in · 127 mm — 0.225 in dia

50d5-1/2 in · 140 mm — 0.244 in dia

60d6 in · 152 mm — 0.263 in dia

US wood-screw gauges, nominal (basic) diameter per ASME B18.6.1:

#20.086 in · 2.2 mm

#30.099 in · 2.5 mm

#40.112 in · 2.8 mm

#50.125 in · 3.2 mm

#60.138 in · 3.5 mm

#70.151 in · 3.8 mm

#80.164 in · 4.2 mm

#90.177 in · 4.5 mm

#100.190 in · 4.8 mm

#120.216 in · 5.5 mm

#140.242 in · 6.1 mm

02 Worked example

Frame a stud wall and the schedule hands you the sizes directly. The default framing nail is the 16d: 3-1/2 in (89 mm) long, 0.162 in (4.1 mm) shank. The IRC fastening schedule uses two of them to end-nail a plate to a stud.

Drop to the toe-nail and the size drops with it. An 8d common is 2-1/2 in (64 mm) long and 0.131 in (3.3 mm) across — four of them toe-nail the same plate-to-stud joint. The shorter nail goes in at an angle, so it needs the length to cross the joint and the thinner shank to turn without splitting the plate.

Switching to screws for the non-structural work on the same wall — blocking for a cabinet, say — the general-purpose choice is a #8 at 0.164 in (4.2 mm), close in diameter to that 16d but specified by thickness, not length. Set the lookup to 16d, then 8d, then the #8 screw and the three read back in order.

03 When this chart is wrong

A flat size chart hides two things that change what you actually buy and whether it holds.

The penny size fixes length, not diameter. There is no penny-to-diameter formula, and the diameter the chart lists is for a common nail. The same designation in box, sinker, or collated-pneumatic form runs thinner: a hand-drive 16d common is 0.162 in, but a pneumatic "16d" framing nail is commonly 0.131–0.135 in — closer to a 10d shank. The thinner nail has less shear and withdrawal capacity, which is why clipped-head gun nails and hand-drive commons are not freely interchangeable in a rated connection. Charts also disagree on the mid sizes themselves: 4d is published anywhere from 0.099 to 0.109 in, 6d from 0.113 to 0.122 in. Read the diameter off the box, not the penny size.
Matching a screw to a nail by size does not make it a code substitute. This is the editorial line of this page: for the structural frame connections in IRC Table R602.3(1), ordinary drywall, deck, and "construction" screws are not a legal replacement for the prescribed nails, whatever their diameter. The schedule is written in nails because nails are ductile and carry lateral and seismic load by bending, while hardened bugle-head screws have high pull-out resistance but are brittle and shear off. A screw replaces a prescribed nail only where it is a code-listed alternative fastener carrying an ICC-ES evaluation report (ESR) under AC233 — i.e., a purpose-made structural wood screw. The exception runs the other way too: several connections assign screws or bolts over nails, such as a deck ledger to the band joist, which takes 1/2 in lag screws or through-bolts and may not be nailed.
Structural connectors take only their specified fastener. Joist hangers, hurricane ties, and straps are load-rated with the connector-specific nails or the manufacturer's structural screws. A nail of the right penny length that is the wrong diameter for the hanger hole, or a deck screw subbed in, voids the published rating. The hole size on the connector, not this chart, sets the fastener.

04 What to do with the result

Use the chart to translate a plan or a fastening schedule into what to grab off the shelf, then verify the diameter against the box for anything structural. For framing, buy by the common nail the schedule names — 16d for plates and studs, 8d for sheathing and toe-nails — and if you are shooting a nail gun, check that the collated nail's listed shank diameter matches what the connection or the braced-wall detail calls for, not just the "16d" on the box.

For screws, pick the gauge by the job — #8 is the default for general wood, decking, and subfloor; step to #10 for heavier attachment — and set the length so the screw buries at least half its length in the receiving member. When the drawing calls out a structural screw by an ESR number, order that exact screw; a same-size deck screw is not the same fastener.

05 Common questions

What does the "d" in nail sizes mean?: It stands for penny, the old unit, abbreviated d from the Roman denarius. It once meant the price per hundred nails; today it is purely a length designation. A 16d nail is 3-1/2 in (89 mm) long, and the "16" tells you nothing about the diameter.
What size is a 16d nail in inches?: 3-1/2 in (89 mm) long. As a common nail the shank is 0.162 in (4.1 mm); as a collated pneumatic nail the same "16d" is usually thinner, around 0.131–0.135 in.
What size nail do I use for framing?: The 16d common is the default for wall framing — plate-to-stud and stud face-nailing per IRC Table R602.3(1). Sheathing and toe-nailing use the 8d common (2-1/2 in, 0.131 in). Follow the fastening schedule for the specific connection and any braced-wall detail.
What gauge is a #8 wood screw?: A #8 screw has a nominal major diameter of 0.164 in (4.2 mm) per ASME B18.6.1. The gauge sets the diameter; the length (e.g. 1-1/4 in, 2-1/2 in) is a separate number on the box.
Can I use screws instead of nails for framing?: Not as a size-for-size swap. For the structural connections in the IRC fastening schedule, ordinary drywall and deck screws are not a code-recognized substitute for the prescribed nails — nails bend and carry shear, hardened screws shear off. Use nails, or a purpose-made structural wood screw carrying an ICC-ES ESR for that connection.
Why do two charts list different diameters for the same nail?: Because the penny size fixes only length, and shank diameter varies by nail type (common, box, sinker, pneumatic) and by manufacturer. The length is standardized; the diameter is not. For a rated connection, read the diameter off the product spec rather than inferring it from the penny size.