US & CAN Diameter EU UK & AU SGP & JP HK CHE
3 14.1mm 44 F 1/2 4 6 4
  14.3mm 45 G 5   5 1/4
3.5 14.5mm   G 1/2   7  
  14.7mm 46 H 6   6 1/2
4 14.9mm 47 H 1/2 7 8  
  15.1mm   I     7 3/4
4.5 15.3mm 48 I 1/2 8 9  
  15.5mm   J   10 9
5 15.7mm 49 J 1/2 9    
  15.9mm 50 K   11 10
5.5 16.1mm   K 1/2 10    
  16.3mm 51 L   12 11 3/4
6 16.5mm 52 L 1/2 11 13 12 3/4
  16.7mm   M 12    
6.5 16.9mm 53 M 1/2 13 14 14
  17.1mm   N      
7 17.3mm 54 N 1/2 14 14 15 1/4
  17.5mm 55 O   16  
7.5 17.7mm   O 1/2 15   16 1/2
  17.9mm 56 P   17  
8 18.1mm 57 P 1/2 16   17 3/4
  18.2mm 58        
  18.3mm   Q      
8.5 18.5mm 58 Q 1/2 17    
  18.8mm 59 R   19 19
9 19mm   R 1/2 18 20  
  19.2mm 60 5     20 1/4
9.5 19.4mm 61 S 1/2 19 21  
  19.6mm   T     21 1/2
10 19.8mm 62 T 1/2 20 22  
  20mm   U 21    
10.5 20.2mm 63 U 1/2 22 23 22 3/4
  20.4mm 64 V   24  
11 20.6mm   V 1/2 23    
  20.8mm 65 W   25 25
11.5 21mm 66 W 1/2 24    
  21.2mm   X   26  
12 21.4mm 67 X 1/2 25 27 27 1/2
  21.6mm   Y   26  
12.5 21.8mm 68 Z 26    
  22mm 69 Z 1/2      
13 22.2mm 70   27    
  22.4mm   Z + 1      
13.5 22.6mm   Z + 2