Wires for ISO general purpose metric screw threads (M)

Measurement of the pitch diameters of ISO general purpose metric screw threads (M) according to ISO 16239 standard. Dimensions are in millimetres.

Nominal diameters of best-size wires and allocated pitches for M threads
Nominal diameter of wires	Pitch P	Nominal diameter of wires	Pitch P
0.115	0.2	0.866	1.5
0.144	0.25	1.010	1.75
0.173	0.3	1.155	2
0.202	0.35	1.443	2.5
0.231	0.4	1.732	3
0.260	0.45	2.021	3.5
0.289	0.5	2.309	4
0.346	0.6	2.598	4.5
0.404	0.7	2.887	5
0.433	0.75	3.175	5.5
0.462	0.8	3.464	6
0.577	1	4.619	8
0.722	1.25	-	-

Note: For symmetric threads, the diameter of a best-size wire is equal to P/(2 cos α/2), where P is the pitch and α/2 is the flank angle.