1/4"-20 Machine Screws

1/4-20 Machine Screws in all available lengths, grades, materials, and finishes.

1/4-20 Thread Specifications

• Nominal diameter: 0.25"
• Threads per inch: 20
• Tap drill (75% thread): #7 (0.201")
• Clearance hole (close fit): 17/64" (0.266")
• Clearance hole (free fit): 9/32" (0.281")

To thread a 1/4-20 hole, drill with a #7 (0.201") tap drill for a standard 75% thread. For a clearance hole that the 1/4-20 screw passes through, use 17/64" (0.266") for a close fit or 9/32" (0.281") for a free fit. Pair with a matching 1/4-20 nut or tapped hole.