Wood Screw Size Chart

Wood Screw Size Charts

Driver Bit Color Codes
Screw Size Driver Size Hand Driver Color (normally)
#4 #0 Bit Light Yellow
#5, 6, 7 #1 Bit Medium Green
#8, 9, 10 #2 Bit Red
#12, 14 #3 Bit Black
#5/16 in.  & up #4 Bit Un–coded;
Shop our selection of Frearson Drive bits to match the wood screws you're ordering.

 

Not sure which size you need? The drawings below are as accurate as possible to help in deciding which size is required for your project. 

 

Screw Size Comparison

Screw Length

Wood Screw Sizing

There is no hard and fast rule concerning screw length requirements.  Sometimes you don't have much choice as to length because of the construction details.  In general though, the screw should always go be sized so that the smooth part of the shank goes through the top, thinner piece of material, and the threaded part of the shank into the thicker piece.  In choosing length, try to have about 2/3 of the screw threaded into the "secondary" piece.  As the thickness of the lumber increases though, this ratio can be reduced so that only 1/2 of the shank is threaded into the secondary piece.  Not coincidentally, only 2/3 of the shank is threaded on our 1 in.  and longer screws.

Screw Dimensions

We've listed screw dimensions for in two forms − a table showing the maximum and minimum decimal dimensions, and a table showing the maximum fractional dimensions.  Note that the fractional dimensions are the best approximations of the actual decimal dimensions.

All of the dimensions are in imperial units.

  "A"
Flat Head
"A"
Pan Head
"A"
Round Washer Head
"B"
Body Dia
"C"
Thread Dia
Size Max Min Max Min T max Max Min T max Max Min Max Min
4 0.225 0.195 0.219 0.205 0.086 N/A N/A N/A 0.095 0.084 0.116 0.105
6 0.279 0.244 0.270 0.256 0.103 N/A N/A N/A 0.118 0.107 0.142 0.131
8 0.332 0.292 0.322 0.306 0.120 0.376 0.352 0.110 0.136 0.125 0.168 0.157
10 0.385 0.340 0.373 0.357 0.137 0.443 0.411 0.125 0.157 0.146 0.194 0.183
12 0.438 0.389 0.425 0.407 0.153 N/A N/A N/A 0.176 0.165 0.220 0.209
14 0.507 0.452 0.492 0.473 0.175 N/A N/A N/A 0.201 0.190 0.246 0.235
Note: IFI Standards specify a tolerance on screw length of +0", −1/16".
  "A"
Flat Head
"A"
Pan Head
"A"
Round Washer Head
"B"
Body Dia
"C"
Thread Dia
Size Max Dia Max Dia T max Max Dia T max Min Max
4 7/32 7/32 3/32 N/A N/A 3/32 1/8
6 9/32 17/64 7/64 N/A N/A 1/8 9/64
8 21/64 21/64 1/8 3/8 7/64 9/64 11/64
10 25/64 3/8 9/64 7/16 1/8 5/32 3/16
12 7/16 27/64 5/32 N/A N/A 11/64 7/32
14 1/2 31/64 11/64 N/A N/A 13/64 1/4
 
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