Pick a thread system and size to get the correct tap drill for 75% thread engagement. Nothing leaves your browser.
Yes, completely, no limit. This is a lookup table and simple arithmetic that runs entirely in your browser, no AI, no backend call at all.
Tap drill size only, at 75% thread engagement, the standard general-purpose target. Metric covers the standard ISO 261 coarse-pitch series (M1.6-M36); ISO fine-pitch threads aren't included since multiple valid fine pitches exist per size and picking "the" one would be arbitrary. UNC and UNF cover the common range from #0 through 1 inch. Torque specs aren't included, torque depends on bolt material, grade, and coating, a meaningfully different (and higher-stakes) calculation than drill size.
Metric tap drill size is computed from the standard formula (major diameter minus pitch), which gives ~75% thread engagement, this is a real geometric derivation, safe to compute directly, not a value that needs to be looked up. UNC and UNF drill designations (number, letter, or fractional) are hardcoded from a published standard tap drill chart, since the inch drill index isn't evenly spaced and can't be derived by formula.
This is a quick reference, not a substitute for a real tap drill chart when tapping expensive or hard-to-replace parts. Harder materials often use a lower engagement percentage (e.g. 50-65%) to reduce tap breakage risk, that's a deliberate departure from this tool's fixed 75% target, not an error.