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Calibration Tap Drill Chart
HOME CALIBRATION RESOURCE CALIBRATION TAP DRILL CHART

   CALIBRATION TAP DRILL CHART

Tap Drill Sizes (inch) for a 75% Thread
 
In general, you can find the tap-drill for any size 60-degree thread, Subtract one pitch length from the major diameter.
 
Formula: Major Dia. minus One Pitch Length equals tap-drill size
 
English Example for 3/8-16 thread: .375 - .0625 = .3125 tap-drill (5/16)
 
Metric Example for M6 X 1 thread: 6mm - 1mm = 5mm tap-drill
 
 

Tap Size Thread Form Tap Drill
0-80 UNF 3/64
1-64 UNC 53
1-72 UNF 53
2-56 UNC 50
2-64 UNF 50
3-48 UNC 47
3-56 UNF 45
4-40 UNC 43
4-48 UNF 42
5-40 UNC 38
5-44 UNF 37
6-32 UNC 36
6-40 UNF 33
8-32 UNC 29
8-36 UNF 29
10-24 UNC 25
10-32    
Tap Size Thread Form Tap Drill
1/4-28 UNF 3
5/16-18 UNC F
5/16-24 UNF I
3/8-16 UNC 5/16
3/8-24 UNF Q
7/16-14 UNC U
7/16-20 UNF 25/64
1/2-13 UNC 27/64
1/2-20 UNF 29/64
9/16-12 UNC 31/64
9/16-18 UNF 33/64
5/8-11 UNC 17/32
5/8-18 UNF 37/64
11/16-11 UNS 19/32
11/16-16 UNS 5/8
3/4-10 UNC 21/32
3/4-16 UNF 11/16
7/8-9 UNC 49/64
7/8-14 UNF 13/16
1-8 UNC 7/8
1-12 UNF 59/64
1-14 UNS 15/16

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