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Metric Screw Thread Series
to 30 mm diameter

For other metric thread series see BA thread series, Löwenherz thread series, Thury thread series, Systeme Francaise.

The green and blue shadings are provided only as an aid to orientation.

In 1898 an international congress held at Zurich (the Congrès International pour l'Unification des Filetages) adopted a thread form similar to the United States Standard thread, except that the roots were rounded. The French had their own SI series.

 

Major Diameter in millimeters Pitch (distance from thread to thread) in millimeters
ISO
1st pref.
ISO
2nd pref.
ISO
3rd pref.
Non-
ISO
ISO
Coarse
ISO
Fine
SI
Fine
SI
coarse
JIS DIN Fine DIN Standard
1       0.25 0.2 0.2 0.25   0.20  
  1.1     0.25 0.2          
1.2       0.25 0.2 0.2 0.25   0.20  
  1.4     0.30 0.2 0.2 0.3   0.20  
1.6       0.35 0.2          
      1.7     0.2 0.35   0.20  
  1.8     0.35 0.25          
2       0.40   0.25 0.4   0.20  
  2.2     0.45 0.35          
      2.3     0.25 0.4   0.25  
2.5       0.45 0.35          
      2.6     0.35 0.45   0.25  
3       0.5 0.35 0.35 0.5 0.6 0.35 0.5
  3.5       0.35 0.35 0.6   0.35  
4       0.70 0.5 0.5 0.7 0.75 0.35 0.7
  4.5       0.5 0.5 0.75   0.5  
5       0.80 0.5 0.5 0.8 0.9 0.5 0.8
    5.5     0.5          
6       1.00 0.75 0.75 1 1 0.75 1
  7     1.00 0.75 0.75 1      
8       1.25 1 1 1.25 1.25 1.0 1.25
    9   1.25   1 1.25      
10       1.5 1.25 1 1.5 1.25 1.0 1.5
    11   1.5            
12       1.75 1.25 1.5 1.75 1.5 1.5 1.75
  14     2.0 1.5 1.5 2 1.5 1.5 2.0
    15                
  16     2.0 1.5 1.5 2 1.5 1.5 2.0
    17                
  18     2.5 1.5  1.5 2.5     2.5
20       2.5 1.5 1.5 2.5     2.5
  22     2.5 1.5 1.5 2.5     2.5
24       3.0 2.0  2 3     3
    25                
    26                
  27     3.0   2 3     3
    28                
30       3.5   2 3.5     3.5

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