TABLE 1  
  ISO METRIC COARSE PITCH  
  FIRST PREFERENCE SERIES  
nom. pitch stress hexagon
size   area a/c flats
d p As s
mm mm mm2 mm
1.6 0.35 1.27 3.2
2 0.4 2.07 4
2.5 0.45 3.39 5
3 0.5 5.03 5.5
4 0.7 8.78 7
5 0.8 14.2 8
6 1 20.1 10
8 1.25 36.6 13
10 1.5 58.0 16
12 1.75 84.3 18
16 2 157 24
20 2.5 245 30
24 3 353 36
30 3.5 561 46
36 4 817 55

Further particulars appear at
www.mech.gla.ac.uk/~paulk/pde/nutbolt1.htm