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Machine Screw Sizes (ASME B18.6.3)

This page lists common machine screw head types and drive types with links to detailed ASME B18.6.3 dimension tables.

Pan Truss Fillister Flat Oval Phillips Slotted Combo

For thread details, see our UN thread calculator and UNC/UNF thread pitch chart. For other charts, visit Fastener size charts.

Head Type Drive Type Dimensions Table
Pan head (machine screw) Combo drive (Phillips + slotted) Combo Pan Head Machine Screw Dimensions
Truss head (machine screw) Combo drive (Phillips + slotted) Combo Truss Head Machine Screw Dimensions
Fillister head (machine screw) Phillips drive Phillips Fillister Head Machine Screw Dimensions
Flat countersunk head (machine screw) Phillips drive Phillips Flat Countersunk Head Machine Screw Dimensions
Oval countersunk head (machine screw) Phillips drive Phillips Oval Countersunk Head Machine Screw Dimensions
Pan head (machine screw) Phillips drive Phillips Pan Head Machine Screw Dimensions
Truss head (machine screw) Phillips drive Phillips Truss Head Machine Screw Dimensions
Drilled fillister head (machine screw) Slotted drive Slotted Drilled Fillister Head Machine Screw Dimensions
Fillister head (machine screw) Slotted drive Slotted Fillister Head Machine Screw Dimensions
Flat countersunk head (machine screw) Slotted drive Slotted Flat Countersunk Head Machine Screw Dimensions
Oval countersunk head (machine screw) Slotted drive Slotted Oval Countersunk Head Machine Screw Dimensions
Pan head (machine screw) Slotted drive Slotted Pan Head Machine Screw Dimensions
Truss head (machine screw) Slotted drive Slotted Truss Head Machine Screw Dimensions

Machine Screw FAQ

ASME B18.6.3 defines dimensional requirements for several inch-series machine screw head styles (for example pan, truss, fillister, flat, and oval) and common drive types.

A combo drive typically accepts both a Phillips and a slotted screwdriver, improving serviceability when one driver type is not available.

Use the UN thread calculator and UNC/UNF pitch chart linked above to confirm thread pitch, tolerances, and related thread data for inch-series machine screws.

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