Machining & CNC unit converters

Convert cutting speeds, feeds, thread pitch, and precision measurements for the machine shop.

• Inches (in) → Millimeters (mm) mm = inches × 25.4
• Thou (mils) (thou) → Millimeters (mm) mm = thou × 0.0254 (1 thou = 0.001 in)
• Surface feet per minute (SFM) → Spindle RPM (RPM) RPM = (SFM × 12) ÷ (π × diameter_in) [diameter defaults to 1.0 in]
• Threads per inch (TPI) → Thread pitch (mm) pitch(mm) = 25.4 ÷ TPI