#4-40 Flat Head Cap Screws

#4-40 Flat Head Socket Cap Screws in all available lengths, grades, materials, and finishes. This collection covers every #4-40 option in stock — use the filters to narrow by length, grade, material, and finish.

#4-40 Thread Specifications

• Nominal diameter: 0.112"
• Threads per inch: 40
• Tap drill (75% thread): #43 (0.089")
• Clearance hole (close fit): #31 (0.120")
• Clearance hole (free fit): #30 (0.128")

To thread a #4-40 hole, drill with a #43 (0.089") tap drill for a standard 75% thread. For a clearance hole that the #4-40 screw passes through, use #31 (0.120") for a close fit or #30 (0.128") for a free fit. Pair with a matching #4-40 nut or tapped hole.

Orders before 12 PM ET ship same day.