Wood Screw Size Chart with Applications
| 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 "Square Drive Driver Bits" and use the filters on the left to find the color bits you are looking for. | ||
Not sure which size you need? We made the drawings below as accurate as possible to help you decide which size you need for your job. In addition, the following guidelines may help you select the proper size:
#4 Designed for small crafts, jewelry boxes, attaching hinges, etc. Extra-light duty.
Available in 3/8 in. to 3/4 in.
Available in 3/8 in. to 3/4 in.
#6 Small crafts, hinges and drawer slides, children’s furniture, toys, light-duty jigs and fixtures, etc., light-duty.
Available in 1/2 in. to 1-1/2 in.
Available in 1/2 in. to 1-1/2 in.
#8 General furniture construction, cabinets, light construction. Good all-purpose.
Available from 5/8 in. to 3 in.
Available from 5/8 in. to 3 in.
#10 General construction, heavy-duty furniture, outdoor projects, decks, lawn furniture, boat building, and more.
Available in sizes from 3/4 in. to 4 in.
Available in sizes from 3/4 in. to 4 in.
#12 & #14 For heavy-duty construction, hanging solid-core doors, etc.
Available in 3/4 in.to 6 in. (#12 shown).
Available in 3/4 in.to 6 in. (#12 shown).
Use our Select A Screw Section. Use the filters on the left side. You can quickly narrow your options to the screws you need.
The McFeelys 2/3 Rule for Screw Length
No hard and fast rule governs screw length requirements. Sometimes you have little choice as to length because of the construction details. In general, though, the screw should always go through the thinner piece and thread into the thicker piece.
In choosing length, try to have about 2/3 of the screw threaded into the "secondary" piece, as shown. As the lumber gets thicker, you can reduce this ratio.
Then only half the shank needs threads in 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 Production Screw dimensions in two formats. One table shows the maximum and minimum decimal dimensions. Another table shows the maximum fractional dimensions. Note that the fractional dimensions are the best approximations of the actual decimal dimensions.
Traditional Wood Screw vs. Modern Production Screw
The difference between a traditional wood screw and a modern production screw is in their sizing.
It uses the diameter of the screw shank and the screw threads as its basis.
Traditional Wood Screws - The shank diameter on this screw exactly matches the outside dimensions of the threads. Threads on these screws are deeper near the point and begin to shallow as they get closer to the unthreaded shank or screw head. Tapered drill bits are needed for this type of screw. The pilot hole should closely match the screw’s outside shank diameter. Creating this tight fit on traditional wood screws yields maximum holding power.
Modern Production Screws - The shank diameter is smaller than the major diameter but larger than the minor diameter. The overall reduced shank
diameter results in a deep thread profile offering great holding power. Drilling a pilot with a straight drill bit yields excellent results because the shank of the screw is straight throughout its entire length. The advantages of this are that straight bits do not require the same critical depth control needed with a tapered bit.
- Minor Diameter: Measurement of the screw body between the threads, from one side to the other. It is smaller than the major diameter and shank diameter.
- Major Diameter: The outside measurement of the thread, from one side to the other. It is larger than the shank and minor diameters.
- Shank Diameter: Measure the bare shank from one side to the other. It is larger than the minor diameter, but smaller than the major diameter.
| "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 |
| "A" Flat Head | "A" Pan Head | "A" Wafer Head Dia | "B" Body Dia | "C" Thread Dia | ||||||||
| 15 | N/A | N/A | N/A | N/A | N/A | 0.620 | 0.179 | 0.202 | 0.275 | |||
| 17 | N/A | N/A | N/A | N/A | N/A | 0.675 | 0.210 | 0.295 | ||||
| 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 | |||||
| "A" Flat Head | "A" Pan Head | "A" Wafer Head Dia | "B" Body Dia | "C" Thread Dia | ||||||||
| 15 | N/A | N/A | N/A | 5/8 | 13/64 | 9/32 | ||||||
| 17 | N/A | N/A | N/A | 11/16 | 7/32 | 19/64 | ||||||
Login and Registration Form