What Size Pilot Hole Needs to Be Drilled for a Quarter-Inch Bolt?

By Staff WriterLast Updated Apr 12, 2020 7:39:56 PM ET

The pilot hole required depends on the density of wood being used. For a 1/4-inch lag bolt attached to softwood, the appropriate pilot hole size is 3/32 inch. Medium-density wood requires a 5/32-inch hole, and hardwood requires a 3/16-inch hole.