Screw Size Guide

For those of you who thought that screw sizing was just guesswork or the cost of the raw materials on the day of manufacture the following information might be of interest to you.

The largest wood screw that Nettlefolds produced was a size 32. The smallest was a size 0000 The shank of the screw at the widest point was exactly half the width of the head.

A size 32 screw was given a head diameter of one inch and a shank diameter of half inch. A size 0000 has a head diameter of 108/1000 of an inch and a shank diameter of 54/1000 of an inch. The diameters of the heads reduced by 28/1000 of an inch, and the shanks reduced by 14/1000 of an inch for each size of screw until they got down to a size 1. They then reduced the diameters by just 6/1000 and 3/1000 respectively.

As most people can grasp metric measurements these days, we have converted the Imperial sizes to Metric to 2 decimal places. I think that rounding up or down should suffice for most of the projects using my Nettlefolds stock.

Screw GaugeHead diameter (mm)Shank diameter (mm)
00002.741.37
0002.891.44
003.041.52
03.201.60
13.351.67
24.062.03
34.772.38
45.482.74
56.193.09
66.903.45
77.623.81
88.334.16
99.044.52
109.754.87
1110.465.23
1211.165.58
1311.885.94
1412.586.29
1513.306.65
1614.027.01
1714.737.36
1815.447.72
1916.148.07
2016.868.43
2117.568.78
2218.989.49
2318.289.14
2419.719.85
2621.3310.56
2822.5511.27
3023.9711.98
3225.4012.70

Screw Lengths

Length (Inches)Length (mm)
¼"6.4mm
⅜"9.5mm
½"12.8mm
⅝"15.9mm
¾"19.1mm
⅞"22.2mm
1"25.4mm
1 ¼"31.8mm
1 ½"38.1mm
1 ¾"44.5mm
2"50.8mm
2 ¼"57.2mm
2 ½"63.5mm
2 ¾"69.9mm
3"76.2mm
3 ¼"82.6mm
3 ½"88.9mm
4"101.6mm
4 ½"114.3mm
5"127.0mm
6"152.4mm