Tap and drill chart for inch UNC and UNF threads, generated from the 75%-thread formula.
Reference aid — verify before you cut. Thread data per ASME B1.1 (Unified), ASME B1.8 (Stub Acme) and ISO 965 (metric M profile); charts cite their source in each tool. Formulas and data are checked against published standards, but errors and edge cases are possible — always confirm critical dimensions against the controlling standard or a calibrated gage before machining. No warranty; use at your own risk. Tap the star on a tool to favorite it.
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Tap drills — 75% target
Drill = major − 0.01299 × % ÷ TPI, snapped to the nearest standard drill (the published chart picks). Cut taps only — roll-form taps need a larger hole. Use the Tap drill tool for other thread percentages. Tap a row to copy the drill size.