Tap & ClearanceDrill Sizes
Precision machining reference for screw sizing and thread engagement. Pick a screw — get the tap drill, clearance hole, and quick link to the right parts.
About
Built by an optical systems engineer and shop fabricator who got tired of digging through PDF tap charts mid-job. This is the reference I wanted on the bench: pick a screw, get the right tap drill and clearance hole, and jump straight to the supplier.
Contact
Wrong value, missing size, or supplier request? contact@tapandclearance.com
Tap drill size chart & clearance hole calculator
This tap drill size chart covers imperial machine screws (#0 through 1") and ISO metric coarse threads (M1.6 through M12), including the most common UNC and UNF thread pitches. For every screw and thread combination it returns the recommended tap drill for soft materials like aluminum, brass, and plastics (75% thread engagement) and for harder materials like steel, stainless, and cast iron (50% thread engagement), along with close-fit and free-fit clearance hole sizes.
Use the units toggle for instant metric to imperial conversion — every drill size is displayed in both inches and millimeters so you can match whichever drill index is on your bench. Looking for clearance hole sizes for M4, the tap drill for 1/4-20, or the right number drill for #10-32? Pick the screw from the dropdown and the answer is one click away, with a direct link to order the matching screw, tap, and drill bit from Zoro, Home Depot, Acme Tools, or McMaster-Carr.
Values are cross-referenced against the ISO 261 metric coarse standard and standard UNC/UNF thread tables. Always confirm against your tap manufacturer's spec for critical work.