How do you calculate tap drill size for metric threads?
For standard 75% thread depth in metric coarse threads: Tap Drill Diameter = Nominal Diameter (d) - Thread Pitch (P). Example: M10 × 1.5 requires an 8.5 mm drill.
Interactive engineering guide for metric coarse and fine thread pitch, pre-tap drill diameters, wrench sizes and thread clearance holes per ISO 261.
Engineered for mechanical, HVAC, piping, and design engineers in compliance with international standards (ISO, DIN, EN, ASME, ASHRAE). Load the interactive tool for real-time calculations and automated reports.
For standard 75% thread depth in metric coarse threads: Tap Drill Diameter = Nominal Diameter (d) - Thread Pitch (P). Example: M10 × 1.5 requires an 8.5 mm drill.