Wood Screw Pilot & Clearance Hole Chart

Prevent split hardwood and stripped heads with exact pilot and clearance drill bit sizes.

Screw Gauge Size Standard North American wood screw sizes

Substrate Wood Type

Hardwood (Oak, Maple, Walnut) Softwood (Pine, Cedar, Fir)

Softwoods compress more and require slightly tighter pilot holes

COMPLETE SHOP GAUGE REFERENCE TABLE

Screw	Clearance	Hardwood Pilot	Softwood Pilot	82° Countersink
#4 (0.112")	1/8"	5/64"	1/16"	1/4"
#5 (0.125")	9/64"	3/32"	5/64"	5/16"
#6 (0.138")	9/64"	7/64"	3/32"	5/16"
#7 (0.151")	11/64"	7/64"	3/32"	5/16"
#8 (0.164")	11/64"	1/8"	7/64"	3/8"
#9 (0.177")	3/16"	9/64"	1/8"	3/8"
#10 (0.19")	3/16"	9/64"	1/8"	7/16"
#12 (0.216")	7/32"	5/32"	9/64"	7/16"
#14 (0.242")	1/4"	11/64"	5/32"	1/2"

Top Board Clearance Hole	11/64" (0.1719")
Hardwood Pilot (Dense)	1/8" (0.1250")
Softwood Pilot (Fibrous)	7/64" (0.1094")
82° Countersink Diameter	3/8" (0.3750")
Screw Shank Major Dia.	11/64" (0.1640")

Always drill the clearance hole entirely through the top board to prevent screw binding and gaps.

How this calculation works

Lookup precise straight drill bit diameters in fractional and decimal inches for wood screw gauges #4 through #14 in both hardwoods and softwoods.

Formula: Clearance Hole = Shank Major Diameter; Pilot Hole = Root Core Diameter (Hardwood) / ~75% Root (Softwood)

Measurement Scope: Covers standard wood screws #4–#14, clearance shank holes, straight pilot bits, and 82° countersinks.

For deep technical background, shop tips, and detailed failure prevention analysis, consult our companion woodworking guide: Read "pilot holes countersinks"