Lag screws
Everything for lag screw pilot holes — the finder by diameter and wood type, and the full chart, ¼" to ¾".
In this section
Lag screw pilot-hole finderPick lag-bolt diameter and wood type and get the pilot-hole size, plus the shank clearance hole.the tool
Lag screw pilot hole chartPilot sizes by lag diameter and wood type, plus the shank clearance hole.full chart
Pilot hole for a 1/4" lag screwSoftwood 3/32" · Hardwood 3/16"
Pilot hole for a 3/8" lag screwSoftwood 11/64" · Hardwood 1/4"
Pilot hole for a 1/2" lag screwSoftwood 15/64" · Hardwood 11/32"
These are general guidance sizes cross-referenced from common woodworking sources. For structural, load-bearing, or manufacturer-specific work, follow the fastener manufacturer’s or an engineer’s specifications.