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  • US Standard Tap Drill Size Chart
  • I.S.O. Metric Spiral Point Tap Chart

  • I.S.O. Metric Spiral Fluted Tap Chart
  • American Taper and Straight Pipe Thread

    • US Standard Tap Drill Size Chart

    Tap Tap Drill Decimal
    Drill Size    		 Theo. %
    of Thread    		 Probable
    Oversize    		 Probable
    Hole Size    		 % of Thread
    0-80 56 .0465 83 .0015 .0480 74
      3/64 .0469 81 .0015 .0480 71
    1-64 54 .0550 89 .0015 .0565 81
      53 .0595 67 .0015 .0610 59
    1-72 53 .0595 75 .0015 .0610 67
      1/16 .0625 58 .0015 .0640 50
    2-56 51 .0670 82 .0017 .0687 74
      50 .0700 69 .0017 .0717 62
      49 .0730 56 .0017 .0747 49
    2-64 50 .0700 79 .0017 .0717 70
      49 .0730 64 .0017 .0747 56
    3-48 48 .0760 85 .0019 .0779 78
      5/64 .0781 77 .0019 .0800 70
      47 .0785 76 .0019 .0804 69
      46 .0810 67 .0019 .0829 60
      45 .0820 63 .0019 .0839 56
    3-56 46 .0810 78 .0019 .0829 69
      45 .0820 73 .0019 .0839 65
      44 .0860 56 .0020 .0880 47
    4-40 44 .0860 80 .0020 .0880 74
      43 .0890 71 .0020 .0910 65
      42 .0935 57 .0020 .0955 51
      3/32 .0938 56 .0020 .0958 50
    4-48 42 .0935 68 .0020 .0955 61
      3/32 .0938 68 .0020 .0958 60
      41 .0960 59 .0020 .0980 52
    5-40 40 .0980 83 .0023 .1003 76
      39 .0995 79 .0023 .1018 71
      38 .1015 72 .0023 .1038 65
      37 .1040 65 .0023 .1063 58
    5-44 38 .1015 79 .0023 .1038 72
      37 .1040 71 .0023 .1063 63
      36 .1065 63 .0023 .1088 55
    6-32 37 .1040 84 .0023 .1063 78
      36 .1065 78 .0023 .1088 72
      7-64 .1094 70 .0026 .1120 64
      35 .1100 69 .0026 .1126 63
      34 .1110 67 .0026 .1136 60
      33 .1130 62 .0026 .1156 55
    6-40 34 .1110 83 .0026 .1136 75
      33 .1130 77 .0026 .1156 69
      32 .1160 68 .0026 .1186 60
    8-32 29 .1360 69 .0029 .1389 62
      28 .1405 58 .0029 .1434 51
    8-36 29 .1360 78 .0029 .1389 70
      28 .1405 68 .0029 .1434 57
      9-64 .1406 68 .0029 .1435 57
    10-24 27 .1440 85 .0032 .1472 79
      26 .1470 79 .0032 .1502 74
      25 .1495 75 .0032 .1527 69
    10-24 24 .1520 70 .0032 .1552 64
      23 .1540 67 .0032 .1572 61
      5/32 .1563 62 .0032 .1595 56
      22 .1570 61 .0032 .1602 55
    10-32 5/32 .1563 83 .0032 .1595 75
      22 .1570 81 .0032 .1602 73
      21 .1590 76 .0032 .1622 68
      20 .1610 71 .0032 .1642 64
      19 .1660 59 .0032 .1692 51
    12-24 11/64 .1719 82 .0035 .1754 75
      17 .1730 79 .0035 .1765 73
      16 .1770 72 .0035 .1805 66
      15 .1800 67 .0035 .1835 60
      14 .1820 63 .0035 .1855 56
    12-28 16 .1770 84 .0035 .1805 77
      15 .1800 78 .0035 .1835 70
      14 .1820 73 .0035 .1855 66
      13 .1850 67 .0035 .1885 59
      3/16 .1875 61 .0035 .1910 54
    1/4-20 9 .1960 83 .0038 .1998 77
      8 .1990 79 .0038 .2028 73
      7 .2010 75 .0038 .2048 70
      13/64 .2013 72 .0038 .2069 66
      6 .2040 71 .0038 .2078 65
      5 .2055 69 .0038 .2093 63
      4 .2090 63 .0038 .2128 57
    1/4-28 3 .2130 80 .0038 .2168 72
      7/32 .2188 67 .0038 .2226 59
      2 .2210 63 .0038 .2248 55
    5/16-18 F .2570 77 .0038 .2608 72
      G .2610 71 .0041 .2651 66
      17/64 .2656 65 .0041 .2697 59
      H .2660 64 .0041 .2701 59
    5/16-24 H .2660 86 .0041 .2701 78
      I .2720 75 .0041 .2761 67
      J .2770 66 .0041 .2811 58
    3/8-16 5/16 .3125 77 .0044 .3169 72
      O .3160 73 .0044 .3204 68
      P .323 64 .0044 .3274 59
    3/8-24 21/64 .3281 87 .0044 .3325 79
      Q .3320 79 .0044 .3364 71
      R .3390 67 .0044 .3434 58
    7/16-14 T .3580 86 .0046 .3626 81
      23/64 .3594 84 .0046 .3640 79
      U .3680 75 .0046 .3726 70
      3/8 .3750 67 .0046 .3796 62
      V .3770 65 .0046 .3816 60
    7/16-20 W .3860 79 .0046 .3906 72
      25/64 .3906 72 .0046 .3952 65
      X .3970 62 .0046 .4016 55
    1/2-13 27/64 .4219 78 .0047 .4266 73
      7/16 .4375 63 .0047 .4422 58
    1/2-20 29/64 .4531 72 .0047 .4578 65
    9/16-12 15/32 .4688 87 .0048 .4736 82
      31/64 .4844 72 .0048 .4892 68
    9/16-18 1/2 .500 87 .0048 .5048 80
      33/64 .5156 65 .0048 .5204 58
    5/8-11 17/32 .5313 79 .0049 .5362 75
      35/64 .5469 66 .0049 .5518 62
    5/8-18 9/16 .5625 87 .0049 .5674 80
      37/64 .5781 65 .0049 .5831 58
    3/4-10 41/64 .6406 84 .0050 .6456 80
      21/32 .6563 72 .0050 .6613 68
    3/4-16 11/16 .6875 77 .0050 .6925 71
    7/8-9 49/64 .7656 76 .0052 .7708 72
      25/32 .7812 65 .0052 .7864 61
    7/8-14 51/64 .7969 84 .0052 .8021 79
      13/16 .8125 67 .0052 .8177 62
    1-8 55/64 .8594 87 .0059 .8653 83
      7/8 .875 77 .0059 .8809 73
      57/64 .8906 67 .0059 .8965 64
      29/32 .9063 58 .0059 .9122 54
    1-12 29/32 .9063 87 .0059 .9122 81
      59/64 .9219 72 .0060 .9279 67
      15/16 .9375 58 .0060 .9435 52
    1-14 59-64 .9219 84 .0060 .9279 78
      15/16 .9375 67 .0060 .9435 61
    1 1/8-7 31/32 .9688 84 .0062 .9750 81
      63/64 .9844 76 .0067 .9911 72
      1 1.000 67 .0070 1.007 64
      1 1/64 1.0156 59 .0070 1.0226 55
    1 1/8-12 1 1/32 1.0313 87 .0071 1.0384 80
      1 3/64 1.0469 72 .0072 1.0541 66
    1 1/4-7 1 3/32 1.0938 84 Reaming Recommended  
      1 7/64 1.1094 76 Reaming Recommended  
      1 1/8 1.125 67 Reaming Recommended  
    1 1/4-12 1 5/32 1.1563 87 Reaming Recommended  
      1 11/64 1.1719 72 Reaming Recommended  
    1 3/8-6 1 3/16 1.1875 87 Reaming Recommended  
      1 13/64 1.2031 79 Reaming Recommended  
      1 7/32 1.2188 72 Reaming Recommended  
      1 15/64 1.2344 65 Reaming Recommended  
    1 3/8-12 1 9/32 1.2813 87 Reaming Recommended  
      1 19/64 1.2969 72 Reaming Recommended  
    1 1/2-6 1 5/16 1.3125 87 Reaming Recommended  
      1 21/64 1.3281 79 Reaming Recommended  
      1 11/32 1.3438 72 Reaming Recommended  
      1 23/64 1.3594 65 Reaming Recommended  
    1 1/2-12 1 13/32 1.4063 87 Reaming Recommended  
      1 27/64 1.4219 72 Reaming Recommended  

    I.S.O. Metric Spiral Point Tap Chart

    Nominal
    Size & Pitch
    (mm)    		 Dimensions - (mm) # of Flutes Shank Dia.
    (mm)    		 Square Size - (mm) Recommended
    Tap Drill
    (mm)
    Thread Length Overall Length Length Width
       M1.6
    M2         		x 0.35
    x 0.4    		 8 41 2 2.5 4 2 1.25
    1.6
    M x 0.5 11 48 2 3.15 5 2.5 2.5
    M3.5 x 0.6 13 50 2 3.55 5 2.8 2.9
    M4
    M4.5    		 x 0.7
    x 0.75     		13 53 2
    2    		 4
    4.5    		 6
    6    		 3.15
    3.55    		 3.3
    3.7
    M5 x 0.8 16 58 2 5 7 4 4.2
    M6
    M7    		 x 1
    x 1     		19 66 2
    3    		 6.3
    7.1    		 8
    8    		 5
    5.6    		 5
    6
    M8 x 1.25 22 72 3 8 9 6.3 6.8
    M10 x 1.5 24 80 3 10 11 8 8.5
    M12 x 1.75 29 89 3 9 10 7.1 10.2
    M14 x 2 30 95 3 11.2 12 9 12
    M16 x 2 32 102 3 12.5 13 10 14
    M18
    M20    		 x 2.5
    x 2.5     		37 112 3 14 14 11.2 15.5
    17.5
    M22 x 2.5 38 118 3 16 16 12.5 19.5
    M24 x 3 45 130 3 18 18 14 21

    I.S.O. Metric Spiral Fluted Tap Chart

    Nominal
    Size & Pitch
    (mm)    		 Dimensions - (mm) # of Flutes Shank Dia.
    (mm)    		 Square Size - (mm) Recommended
    Tap Drill
    (mm)
    Thread Length Overall Length Length Width
       M3 x 0.5 11 48 2 3.15 5 2.5 2.5
    M3.5 x 0.6 13 50 2 3.55 5 2.8 2.9
    M4 x 0.7 13 53 2 4 6 3.15 3.3
    M5 x 0.8 16 58 3 5 7 4 4.2
    M6
    M7    		 x 1
    x 1     		19 66 3 6.3
    7.1    		 8
    8    		 5
    5.6    		 5
    6
    M8 x 1.25 22 72 3 8 9 6.3 6.8
    M10 x 1.5 24 80 3 10 11 8 8.5
    M12 x 1.75 29 89 3 9 10 7.1 10.2
    M14 x 2 30 95 3 11.2 12 9 12
    M16 x 2 32 102 3 12.5 13 10 14
    M18
    M20    		 x 2.5
    x 2.5     		37 112 3 14 14 11.2 15.5
    17.5
    M22 x 2.5 38 118 3 16 16 12.5 19.5
    M24 x 3 45 130 3 18 18 14 21

    American Taper and Straight Pipe Thread

    TAPER PIPE - NPT
    TAP SIZE DRILL SIZE
    1/8" - 27 R
    1/4" - 18 7/16
    3/8" - 18 37/64
    1/2" - 14 23/32
    3/4" - 14 59/64
    1"- 11-1/2 1-5/32
    1-1/4"-11-1/2 1-1/2
    1-1/2"-11-1/2 1-47/64
    2"-11-1/2 2-7/32
    2-1/2"- 8 2-5/8
    3"- 8 3-1/4
    3-1/2"- 8 3-3/4
    4"- 8 4-1/4
    STRAIGHT PIPE - NPS
    TAP SIZE DRILL SIZE
    1/8"- 27 S
    1/4"- 18 29/64
    3/8"- 18 19/32
    1/2"-14 47/64
    3/4"-14 15/16
    1"-11-1/2 1-3/16
    1-1/4"-11-1/2 1-33/64
    1-1/2"-11-1/2 1-3/4
    2"-11-1/2 2-7/32
    2-1/2"- 8 2-21/32
    3"- 8 3-9/32
    3-1/2"- 8 3-25/32
    4"- 8 4-9/32
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