The charts below show metric bolt conversions to standard bolt conversions and DIN numbers for fasteners. To assist in ordering, we offer metric bolt conversion data for industrial bolts/rods, machine screws, and small-diameter fasteners, including approximate equivalency and common DIN numbers.

Below is a table common fastener sizes and lengths and their US (Inch) decimal and closest fraction equivalent. Note - Metric screw diameters usually start with "M" (M3, M4, M5...), for this chart you can just drop the 'M' from the front and add an extra at the back (M3 = 3mm, M4 = 4mm...).

1.0629. M30. 30. 1.181. METRIC SIZE COMPARED TO STANDARD SIZE. For those of us who just refuse to think metric. Approximate size comparison. MM. INCH.

Thread conversion table. Due to the differences in thread angles and pitches, the thread sizes shown below are not directly interchangeable with each other. This table is only to help find a nearest equivalent sized fastener. Table showing nearest thread equivalents - Metric, Metric Fine, BSW, UNC, UNF.

Fastener and Screw / Bolt Design, Formula and Calculations. The following table chart defines standard metric external thread size M1.6 to M18 per. ANSI/ASME B1.13M-1995. These thread sizes and classes represent bolts and screws, as well, as other standard external threads.