Formula and precision policy
mm = inch × 25.4 → 3 × 25.4 = 76.2000 mm
The exact conversion uses 1 inch = 25.4 mm. This page displays 76.2000 mm by default. For CNC, inspection, RFQ, or supplier documents, keep the precision required by the drawing, tolerance block, process plan, or inspection equipment.
Manufacturing context and caveat
A 3 inch value is common in stock and layout work. Convert to 76.2000 mm, then check drawing notes before cutting or ordering material.
Reference-only caveat: this conversion does not certify tolerance, fit, pressure, load, code compliance, material equivalence, or interchangeability. Confirm the controlling drawing, standard, supplier data, and engineering approval before manufacturing.