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Pilot Hole Sizes for Metal Screws and Wood Screws

Posted 30 January, 2010 at 9:43pm by Michael Chu
(Filed under: Life)

While installing shelving in my home, I had to drill pilot holes for #8 and #12 Metal Screws into studs. The problem was, I didn't know how big to drill the holes and when the holes were too small, it was quite difficult to drive the screws into place. I didn't want to make the pilot holes too big because I wanted the shelves to be as sturdy as possible, so I ended up eyeballing the bits (so the shank of the screw would be covered but not the threads) then moving up in size one at a time until I could drive the screws in. Later, I looked up the bit sizes for the screws and decided to post them here for future reference. Hopefully, they will be of help to others as well.

Metal Screws
Screw Size Bit
#4 3/32"
#6 7/64"
#8 1/8"
#10 9/64"
#12 5/32"
#14 (1/4") 3/16"
5/16" 1/4"

Wood Screws - Hard Wood
Screw Size Tapered Bit Straight Bit
2 3/32 1/16
3 7/64 5/64
4 7/64 5/64
5 1/8 3/32
6 9/64 7/64
7 5/32 7/64
8 11/64 1/8
9 3/16 9/64
10 13/64 9/64
12 7/32 5/32
14 1/4 11/64
16 9/32 3/16
18 5/16 7/32
20 21/64 15/64
24 3/8 17/64

Wood Screws - Soft Wood
Screw Size Tapered Bit Straight Bit
2 5/64 1/16
3 3/32 1/16
4 3/32 1/16
5 7/64 5/64
6 1/8 3/32
7 9/64 3/32
8 5/32 7/64
9 11/64 1/8
10 3/16 1/8
12 13/64 9/64
14 15/64 5/32
16 17/64 11/64
18 19/64 13/64
20 5/16 7/32
24 3/8 1/4

Wood Screws - Counter Sink Size
Screw Size Counter Sink Size
2 1/4
3 1/4
4 1/4
5 5/16
6 5/16
7 5/16
8 3/8
9 3/8
10 7/16
12 7/16
14 1/2
16 9/16
18 5/8
20 3/4
24 3/4

4 comments to Pilot Hole Sizes for Metal Screws and Wood Screws

Scott, January 30th, 2010 at 9:59 pm:

  • Greatest book in the history of mankind:
    http://www.amazon.com/Pocket-Ref-Thomas-J-Glover/dp/1885071000

    Everyone should have one. It has every little nugget of information like those measurements you posted, the relative density of metals, strengths of different types of rope, "10" radio codes, Air Force ranks, Airport elevations, greek alphabet, North American area codes sorted by state, birthstones by month, planetary date on Jupiter, the effects of different oils on bolt torque, etc etc.

    The only problem with this book…if you loan it out, you'll never get it back. :-p

Dave Skolnick, February 13th, 2010 at 7:02 am:

  • If you don't already do it, try lubricating the threads of your screw with soap (I have always used cake soap, and have never tried liquid soap). It makes driving the screws in much easier and has no discernible impact on holding.

    - dave

Scott, February 13th, 2010 at 11:35 am:

  • Candle wax works, too.

Ken, June 1st, 2013 at 9:29 am:

  • Thank you for posting this. It was very helpful! =)

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