Based on approximately 75% of full thread
TAP   THREAD FORM CLOSEST FRACTIONAL CLOSEST METRIC CLOSEST LETTER CLOSEST WIRE GAUGE
#0 - 80 NF 3/64 M1.2   #54
#1 - 64 NC 1/16 M1.45   #53
#1 - 72 NF 1/16 M1.5   #53
#2 - 56 NC 1/16 M1.75   #50
#2 - 64 NF 5/64 M1.8   #50
#3 - 48 NC 5/64 M2.0   #47
#3 - 56 NF 5/64 M2.1   #45
#4 - 40 NC 3/32 M2.25   #43
#4 - 48 NF 3/32 M2.35   #42
#5 - 40 NC 3/32 M2.55   #38
#5 - 44 NF 7/64 M2.6   #37
#6 - 32 NC 7/64 M2.75   #35
#6 - 40 NF 7/64 M2.9   #33
#8 - 32 NC 9/64 M3.4   #29
#8 - 36 NF 9/64 M3.5   #29
#10 - 24 NC 5/32 M3.8   #25
#10 - 32 NF 5/32 M4.0   #21
#12 - 24 NC 11/64 M4.5   #16
#12 - 28 NF 3/16 M4.6   #14
1/4 - 20 NC 13/64 M5.0   #7
1/4 - 28 NF 7/32 M5.5   #3
5/16 - 18 NC 17/64 M6.5 F  
5/16 - 24 NF 17/64 M7.0 I  
3/8 - 16 NC 5/16 M8.0 O  
3/8 - 24 NF 21/64 M8.5 Q  
7/16 - 14 NC 23/64 M9.5 U  
7/16 - 20 NF 25/64 M9.9 W  
1/2 - 13 NC 27/64 M10.8    
1/2 - 20 NF 29/64 M11.5    
9/16 - 12 NC 31/64 M12.25    
9/16 - 18 NF 33/64 M12.9    
5/8 - 11 NC 17/32 M13.6    
5/8 - 18 NF 37/64 M14.5    
3/4 - 10 NC 21/32 M16.5    
3/4 - 16 NF 11/16 M17.5    
7/8 - 9 NC 49/64 M19.5    
7/8 - 14 NF 13/64 M20.5    
1 - 8 NC 7/8 M22.5    
1 - 12 NF 15/16 M23.5    
1-1/8 - 7 NC 63/64 M25.0    
1-1/8 - 12 NF 1-3/64 M26.5    
1-1/4 - 7 NC 1-7/64 M28.0    
1-1/4 - 12 NF 1-11/64 M29.5    
1-3/8 - 6 NC 1-7/32 M31.0    
1-3/8 - 12 NF 1-19/64 M33.0    
1-1/2 - 6 NC 1-11/32 M34.0    
1-1/2 - 12 NF 1-27/64 M36.0    
1-3/4 - 5 NC 1-9/16 M39.5    
2 - 4-1/2 NC 1-25/32 M45.5    
2-1/4 - 4-1/2 NC 2-1/32 M51.5    
2-1/2 - 4 NC 2-1/4 M57.5    
3 - 4 NC 2-3/4 M70.0    
3-1/2 - 4 NC 3-1/4 M82.5    

THREAD FORM SYMBOLS
NC - American National Coarse Thread Series
NF - American National Fine Thread Series
NS - American National Thread Special

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