Wood screws are available in lengths from one quarter inch to 6 inches in gauge numbers from 0 to 24, 24 representing the largest available diameter. The available gauge numbers vary for any given screw length. As illustrated in the chart below, a screw one-quarter inch long is available in gauge numbers from 0 to 3, while a three-eighths inch screw is available in gauge numbers from 2 to 7. From one gauge number to the next, the wood screw changes by 13/1000 of an inch.
Use the following formula to determine the diameter of a given gauge number or the gauge number of a given diameter.
N = Gauge Number/D = Diameter
D = (NX0.013)+0.06
N = (D-0.06)/0.013
For example, a screw with a gauge number of 2 has a diameter of 0.086. As indicated in the formula. (2x0.013) + 0.06 = 0.086.
COMMON WOOD SCREWS
Length
Available Gauge Numbers
1/4 inch
0
1
2
3
3/8 inch
2
3
4
5
6
7
1/2 inch
2
3
4
5
6
7
8
5/8 inch
3
4
5
6
7
8
9
10
3/4 inch
4
5
6
7
8
9
10
11
7/8 inch
6
7
8
9
10
11
12
1 inch
6
7
8
9
10
11
12
14
1-1/4 inch
7
8
9
10
11
12
14
16
1-1/2 inch
6
7
8
9
10
11
12
14
16
18
1-3/4 inch
8
9
10
11
12
14
16
18
20
2 inch
8
9
10
11
12
14
16
18
20
2-1/4 inch
9
10
11
12
14
16
18
20
2-1/2 inch
12
14
16
18
20
2-3/4 inch
14
16
18
20
3 inch
16
18
20
3-1/2 inch
18
20
24
4 inch
18
20
24
Bon Tool Co. has made a serious effort to provide exact and current information, but does not guarantee the accuracy of the data. Bon Tool Co. cannot assume responsibility for the application of information nor guarantee results.
