#4 Diameter Screws

Welcome to the “4-Diameter Screws” collection at Old West Iron. This section organizes our screws by shank diameter (also called gauge), so you can select by the thickness of the screw shaft rather than head size. The #4 category represents screws with a moderate-shaft diameter — useful for light- to medium-duty woodworking, trim, and furniture projects where a #3 would be too small and heavier gauges (#6, #8, etc.) would be overkill.

FAQ

Q: What does “#4” mean when referring to screw size?
A: The “#4” is the gauge of the screw — it refers to the diameter of the screw’s shank (the shaft), not the head. In imperial-gauge sizing, the gauge indicates how thick the screw is. 

Q: Why is the screw grouped by shank diameter instead of head size?
A: Because for structural and functional purposes — strength, pilot-hole size, and how the screw interacts with the material — the shank (or outside thread diameter) is the critical dimension. Head size affects only appearance or how the screw sits in or on the material.

Q: When should I choose a #4 screw?
A: A #4 screw works well for lighter tasks where you don’t need great structural strength — for instance attaching trim, hardware, or light cabinetry, or whenever you want a smaller hole and less wood displacement.

Q: Will I find different head types under the #4 grouping?
A: Yes. Because we group by shank diameter, screws under #4 might vary in head style (flat head, round head, decorative head, etc.). Head style affects installation method or appearance, but not the nominal strength or gauge of the screw.

Q: Is there a clear way to know what pilot-hole or clearance hole to drill for a #4 screw?
A: Yes — the shank diameter (gauge) informs pilot-hole size. For #4-gauge screws, refer to a screw-size chart or guide that matches the gauge to recommended pilot-hole diameter for your material.