Tap & ClearanceDrill Sizes

This tap drill chart and clearance hole calculator covers imperial (SAE) machine screws from #0 to 1" and ISO metric coarse threads from M1.6 to M12, with the most common UNC and UNF thread pitches. For every screw and pitch it returns the recommended tap drill size for soft materials like aluminum, brass, and plastics (75% thread engagement) and for harder materials like steel, stainless, and cast iron (50% thread engagement), plus close-fit and free-fit clearance hole sizes.

Toggle the units for instant metric-to-imperial conversion — every drill size is shown in both inches and millimeters, including the number, letter, and fractional sizes for inch screws, so you can match whatever drill index is on your bench. Need the clearance hole for M4, the tap drill for 1/4-20, or the number drill for #10-32? Pick the screw from the dropdown and the answer is one click away, with direct links to order the matching screw, tap, and drill bit from Zoro, Home Depot, Acme Tools, or McMaster-Carr.

Sizes are cross-referenced against the ISO 261 metric coarse standard and the UNC/UNF (ASME B1.1) thread tables. Always confirm against your tap manufacturer's spec for critical work.