METRIC TO INCH SCREW THREAD CONVERSION

Designaton	Body Diameter mm (in)	Typical Pitch in mm*	Threads per Inch
M1	1 (.0393)	0.25	101.6
M1.6	1.6 (.0629)	0.35	72.6
M2	2 (.0787)	0.40	63.5
M2.5	2.5 (.0984)	0.45	56.5
M3	3 (.1181)	0.50	50.8
M3.5	3.5 (.1378)	0.60	42.3
M4	4 (.1574)	0.70	36.3
M5	5 (.1968)	0.80	31.8
M6	6 (.2362)	1.00	25.4
M8	8 (.3149)	1.25	20.3
M10	10 (.3937)	1.50	16.9

*Instead of using Threads per Millimeter, standards use the inverse for metric pitch

Specifying Threads

Much Fancier Chart

Metric Conversion Tables (Javascript)

Screwdriver Size for Round Head Bolts

	DIN*		JIS**
	Head Dia.	Driver Size	Head Dia	Driver Size
M2	4mm	1	3.5mm	1
M2.5	5mm	1	4.5mm	1
M3	6mm	1	5.5mm	2
M3.5	7mm	2	6mm	2
M4	8mm	2	7mm	2
M5	10mm	2	9mm	2
M6	12mm	3	10.5mm	3
M8	16mm	4	14mm	3

*Deutsche Institut fuer Normung (German)
** Japanese Industrial Standards