{
 "title": "Tap drill sizes for metric, UNC and UNF threads",
 "publisher": "MachinistCharts",
 "source": "https://machinistcharts.com/",
 "updated": "2026-10-05",
 "license": "CC BY 4.0, attribution: MachinistCharts (machinistcharts.com)",
 "method": "Cut-tap drill sizes. Thread percent = (D - drill) / (0.01299 x P), equivalent to 76.98 x (D - drill) / P for metric; for inch threads P = 1/TPI.",
 "standards": [
  "ISO 724, ISO general-purpose metric screw threads, basic dimensions",
  "ASME B1.1, Unified inch screw threads (UN and UNR thread form)"
 ],
 "note": "General reference values for steel fasteners. Follow the manufacturer's specification when one exists.",
 "rows": [
  {
   "thread": "M1.6 x 0.35",
   "series": "metric coarse",
   "major_diameter_mm": 1.6,
   "pitch_mm": 0.35,
   "tap_drill": "1.25 mm",
   "tap_drill_mm": 1.25,
   "tap_drill_in": 0.0492,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/m1-6/"
  },
  {
   "thread": "M2 x 0.4",
   "series": "metric coarse",
   "major_diameter_mm": 2,
   "pitch_mm": 0.4,
   "tap_drill": "1.6 mm",
   "tap_drill_mm": 1.6,
   "tap_drill_in": 0.063,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/m2/"
  },
  {
   "thread": "M2.5 x 0.45",
   "series": "metric coarse",
   "major_diameter_mm": 2.5,
   "pitch_mm": 0.45,
   "tap_drill": "2.05 mm",
   "tap_drill_mm": 2.05,
   "tap_drill_in": 0.0807,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/m2-5/"
  },
  {
   "thread": "M3 x 0.5",
   "series": "metric coarse",
   "major_diameter_mm": 3,
   "pitch_mm": 0.5,
   "tap_drill": "2.5 mm",
   "tap_drill_mm": 2.5,
   "tap_drill_in": 0.0984,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/m3/"
  },
  {
   "thread": "M3.5 x 0.6",
   "series": "metric coarse",
   "major_diameter_mm": 3.5,
   "pitch_mm": 0.6,
   "tap_drill": "2.9 mm",
   "tap_drill_mm": 2.9,
   "tap_drill_in": 0.1142,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/m3-5/"
  },
  {
   "thread": "M4 x 0.7",
   "series": "metric coarse",
   "major_diameter_mm": 4,
   "pitch_mm": 0.7,
   "tap_drill": "3.3 mm",
   "tap_drill_mm": 3.3,
   "tap_drill_in": 0.1299,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/m4/"
  },
  {
   "thread": "M5 x 0.8",
   "series": "metric coarse",
   "major_diameter_mm": 5,
   "pitch_mm": 0.8,
   "tap_drill": "4.2 mm",
   "tap_drill_mm": 4.2,
   "tap_drill_in": 0.1654,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/m5/"
  },
  {
   "thread": "M6 x 1",
   "series": "metric coarse",
   "major_diameter_mm": 6,
   "pitch_mm": 1.0,
   "tap_drill": "5 mm",
   "tap_drill_mm": 5.0,
   "tap_drill_in": 0.1969,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/m6/"
  },
  {
   "thread": "M8 x 1.25",
   "series": "metric coarse",
   "major_diameter_mm": 8,
   "pitch_mm": 1.25,
   "tap_drill": "6.8 mm",
   "tap_drill_mm": 6.8,
   "tap_drill_in": 0.2677,
   "thread_percent": 74,
   "url": "https://machinistcharts.com/tap-drill/m8/"
  },
  {
   "thread": "M10 x 1.5",
   "series": "metric coarse",
   "major_diameter_mm": 10,
   "pitch_mm": 1.5,
   "tap_drill": "8.5 mm",
   "tap_drill_mm": 8.5,
   "tap_drill_in": 0.3346,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/m10/"
  },
  {
   "thread": "M12 x 1.75",
   "series": "metric coarse",
   "major_diameter_mm": 12,
   "pitch_mm": 1.75,
   "tap_drill": "10.2 mm",
   "tap_drill_mm": 10.2,
   "tap_drill_in": 0.4016,
   "thread_percent": 79,
   "url": "https://machinistcharts.com/tap-drill/m12/"
  },
  {
   "thread": "M14 x 2",
   "series": "metric coarse",
   "major_diameter_mm": 14,
   "pitch_mm": 2.0,
   "tap_drill": "12 mm",
   "tap_drill_mm": 12.0,
   "tap_drill_in": 0.4724,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/m14/"
  },
  {
   "thread": "M16 x 2",
   "series": "metric coarse",
   "major_diameter_mm": 16,
   "pitch_mm": 2.0,
   "tap_drill": "14 mm",
   "tap_drill_mm": 14.0,
   "tap_drill_in": 0.5512,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/m16/"
  },
  {
   "thread": "M18 x 2.5",
   "series": "metric coarse",
   "major_diameter_mm": 18,
   "pitch_mm": 2.5,
   "tap_drill": "15.5 mm",
   "tap_drill_mm": 15.5,
   "tap_drill_in": 0.6102,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/m18/"
  },
  {
   "thread": "M20 x 2.5",
   "series": "metric coarse",
   "major_diameter_mm": 20,
   "pitch_mm": 2.5,
   "tap_drill": "17.5 mm",
   "tap_drill_mm": 17.5,
   "tap_drill_in": 0.689,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/m20/"
  },
  {
   "thread": "M22 x 2.5",
   "series": "metric coarse",
   "major_diameter_mm": 22,
   "pitch_mm": 2.5,
   "tap_drill": "19.5 mm",
   "tap_drill_mm": 19.5,
   "tap_drill_in": 0.7677,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/m22/"
  },
  {
   "thread": "M24 x 3",
   "series": "metric coarse",
   "major_diameter_mm": 24,
   "pitch_mm": 3.0,
   "tap_drill": "21 mm",
   "tap_drill_mm": 21.0,
   "tap_drill_in": 0.8268,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/m24/"
  },
  {
   "thread": "M27 x 3",
   "series": "metric coarse",
   "major_diameter_mm": 27,
   "pitch_mm": 3.0,
   "tap_drill": "24 mm",
   "tap_drill_mm": 24.0,
   "tap_drill_in": 0.9449,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/m27/"
  },
  {
   "thread": "M30 x 3.5",
   "series": "metric coarse",
   "major_diameter_mm": 30,
   "pitch_mm": 3.5,
   "tap_drill": "26.5 mm",
   "tap_drill_mm": 26.5,
   "tap_drill_in": 1.0433,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/m30/"
  },
  {
   "thread": "M33 x 3.5",
   "series": "metric coarse",
   "major_diameter_mm": 33,
   "pitch_mm": 3.5,
   "tap_drill": "29.5 mm",
   "tap_drill_mm": 29.5,
   "tap_drill_in": 1.1614,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/m33/"
  },
  {
   "thread": "M36 x 4",
   "series": "metric coarse",
   "major_diameter_mm": 36,
   "pitch_mm": 4.0,
   "tap_drill": "32 mm",
   "tap_drill_mm": 32.0,
   "tap_drill_in": 1.2598,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/m36/"
  },
  {
   "thread": "M39 x 4",
   "series": "metric coarse",
   "major_diameter_mm": 39,
   "pitch_mm": 4.0,
   "tap_drill": "35 mm",
   "tap_drill_mm": 35.0,
   "tap_drill_in": 1.378,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/m39/"
  },
  {
   "thread": "M42 x 4.5",
   "series": "metric coarse",
   "major_diameter_mm": 42,
   "pitch_mm": 4.5,
   "tap_drill": "37.5 mm",
   "tap_drill_mm": 37.5,
   "tap_drill_in": 1.4764,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/m42/"
  },
  {
   "thread": "M48 x 5",
   "series": "metric coarse",
   "major_diameter_mm": 48,
   "pitch_mm": 5.0,
   "tap_drill": "43 mm",
   "tap_drill_mm": 43.0,
   "tap_drill_in": 1.6929,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/m48/"
  },
  {
   "thread": "M3 x 0.35",
   "series": "metric fine",
   "major_diameter_mm": 3,
   "pitch_mm": 0.35,
   "tap_drill": "2.65 mm",
   "tap_drill_mm": 2.65,
   "tap_drill_in": 0.1043,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/m3x0-35/"
  },
  {
   "thread": "M4 x 0.5",
   "series": "metric fine",
   "major_diameter_mm": 4,
   "pitch_mm": 0.5,
   "tap_drill": "3.5 mm",
   "tap_drill_mm": 3.5,
   "tap_drill_in": 0.1378,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/m4x0-5/"
  },
  {
   "thread": "M5 x 0.5",
   "series": "metric fine",
   "major_diameter_mm": 5,
   "pitch_mm": 0.5,
   "tap_drill": "4.5 mm",
   "tap_drill_mm": 4.5,
   "tap_drill_in": 0.1772,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/m5x0-5/"
  },
  {
   "thread": "M6 x 0.75",
   "series": "metric fine",
   "major_diameter_mm": 6,
   "pitch_mm": 0.75,
   "tap_drill": "5.2 mm",
   "tap_drill_mm": 5.2,
   "tap_drill_in": 0.2047,
   "thread_percent": 82,
   "url": "https://machinistcharts.com/tap-drill/m6x0-75/"
  },
  {
   "thread": "M8 x 1",
   "series": "metric fine",
   "major_diameter_mm": 8,
   "pitch_mm": 1.0,
   "tap_drill": "7 mm",
   "tap_drill_mm": 7.0,
   "tap_drill_in": 0.2756,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/m8x1/"
  },
  {
   "thread": "M10 x 1",
   "series": "metric fine",
   "major_diameter_mm": 10,
   "pitch_mm": 1.0,
   "tap_drill": "9 mm",
   "tap_drill_mm": 9.0,
   "tap_drill_in": 0.3543,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/m10x1/"
  },
  {
   "thread": "M10 x 1.25",
   "series": "metric fine",
   "major_diameter_mm": 10,
   "pitch_mm": 1.25,
   "tap_drill": "8.8 mm",
   "tap_drill_mm": 8.8,
   "tap_drill_in": 0.3465,
   "thread_percent": 74,
   "url": "https://machinistcharts.com/tap-drill/m10x1-25/"
  },
  {
   "thread": "M12 x 1.25",
   "series": "metric fine",
   "major_diameter_mm": 12,
   "pitch_mm": 1.25,
   "tap_drill": "10.8 mm",
   "tap_drill_mm": 10.8,
   "tap_drill_in": 0.4252,
   "thread_percent": 74,
   "url": "https://machinistcharts.com/tap-drill/m12x1-25/"
  },
  {
   "thread": "M12 x 1.5",
   "series": "metric fine",
   "major_diameter_mm": 12,
   "pitch_mm": 1.5,
   "tap_drill": "10.5 mm",
   "tap_drill_mm": 10.5,
   "tap_drill_in": 0.4134,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/m12x1-5/"
  },
  {
   "thread": "M14 x 1.5",
   "series": "metric fine",
   "major_diameter_mm": 14,
   "pitch_mm": 1.5,
   "tap_drill": "12.5 mm",
   "tap_drill_mm": 12.5,
   "tap_drill_in": 0.4921,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/m14x1-5/"
  },
  {
   "thread": "M16 x 1.5",
   "series": "metric fine",
   "major_diameter_mm": 16,
   "pitch_mm": 1.5,
   "tap_drill": "14.5 mm",
   "tap_drill_mm": 14.5,
   "tap_drill_in": 0.5709,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/m16x1-5/"
  },
  {
   "thread": "M18 x 1.5",
   "series": "metric fine",
   "major_diameter_mm": 18,
   "pitch_mm": 1.5,
   "tap_drill": "16.5 mm",
   "tap_drill_mm": 16.5,
   "tap_drill_in": 0.6496,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/m18x1-5/"
  },
  {
   "thread": "M20 x 1.5",
   "series": "metric fine",
   "major_diameter_mm": 20,
   "pitch_mm": 1.5,
   "tap_drill": "18.5 mm",
   "tap_drill_mm": 18.5,
   "tap_drill_in": 0.7283,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/m20x1-5/"
  },
  {
   "thread": "M22 x 1.5",
   "series": "metric fine",
   "major_diameter_mm": 22,
   "pitch_mm": 1.5,
   "tap_drill": "20.5 mm",
   "tap_drill_mm": 20.5,
   "tap_drill_in": 0.8071,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/m22x1-5/"
  },
  {
   "thread": "M24 x 2",
   "series": "metric fine",
   "major_diameter_mm": 24,
   "pitch_mm": 2.0,
   "tap_drill": "22 mm",
   "tap_drill_mm": 22.0,
   "tap_drill_in": 0.8661,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/m24x2/"
  },
  {
   "thread": "M27 x 2",
   "series": "metric fine",
   "major_diameter_mm": 27,
   "pitch_mm": 2.0,
   "tap_drill": "25 mm",
   "tap_drill_mm": 25.0,
   "tap_drill_in": 0.9843,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/m27x2/"
  },
  {
   "thread": "M30 x 2",
   "series": "metric fine",
   "major_diameter_mm": 30,
   "pitch_mm": 2.0,
   "tap_drill": "28 mm",
   "tap_drill_mm": 28.0,
   "tap_drill_in": 1.1024,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/m30x2/"
  },
  {
   "thread": "#1-64",
   "series": "UNC",
   "major_diameter_in": 0.073,
   "tpi": 64,
   "tap_drill": "#53",
   "tap_drill_mm": 1.51,
   "tap_drill_in": 0.0595,
   "thread_percent": 67,
   "url": "https://machinistcharts.com/tap-drill/1-64/"
  },
  {
   "thread": "#2-56",
   "series": "UNC",
   "major_diameter_in": 0.086,
   "tpi": 56,
   "tap_drill": "#50",
   "tap_drill_mm": 1.78,
   "tap_drill_in": 0.07,
   "thread_percent": 69,
   "url": "https://machinistcharts.com/tap-drill/2-56/"
  },
  {
   "thread": "#3-48",
   "series": "UNC",
   "major_diameter_in": 0.099,
   "tpi": 48,
   "tap_drill": "#47",
   "tap_drill_mm": 1.99,
   "tap_drill_in": 0.0785,
   "thread_percent": 76,
   "url": "https://machinistcharts.com/tap-drill/3-48/"
  },
  {
   "thread": "#4-40",
   "series": "UNC",
   "major_diameter_in": 0.112,
   "tpi": 40,
   "tap_drill": "#43",
   "tap_drill_mm": 2.26,
   "tap_drill_in": 0.089,
   "thread_percent": 71,
   "url": "https://machinistcharts.com/tap-drill/4-40/"
  },
  {
   "thread": "#5-40",
   "series": "UNC",
   "major_diameter_in": 0.125,
   "tpi": 40,
   "tap_drill": "#38",
   "tap_drill_mm": 2.58,
   "tap_drill_in": 0.1015,
   "thread_percent": 72,
   "url": "https://machinistcharts.com/tap-drill/5-40/"
  },
  {
   "thread": "#6-32",
   "series": "UNC",
   "major_diameter_in": 0.138,
   "tpi": 32,
   "tap_drill": "#36",
   "tap_drill_mm": 2.71,
   "tap_drill_in": 0.1065,
   "thread_percent": 78,
   "url": "https://machinistcharts.com/tap-drill/6-32/"
  },
  {
   "thread": "#8-32",
   "series": "UNC",
   "major_diameter_in": 0.164,
   "tpi": 32,
   "tap_drill": "#29",
   "tap_drill_mm": 3.45,
   "tap_drill_in": 0.136,
   "thread_percent": 69,
   "url": "https://machinistcharts.com/tap-drill/8-32/"
  },
  {
   "thread": "#10-24",
   "series": "UNC",
   "major_diameter_in": 0.19,
   "tpi": 24,
   "tap_drill": "#25",
   "tap_drill_mm": 3.8,
   "tap_drill_in": 0.1495,
   "thread_percent": 75,
   "url": "https://machinistcharts.com/tap-drill/10-24/"
  },
  {
   "thread": "#12-24",
   "series": "UNC",
   "major_diameter_in": 0.216,
   "tpi": 24,
   "tap_drill": "#16",
   "tap_drill_mm": 4.5,
   "tap_drill_in": 0.177,
   "thread_percent": 72,
   "url": "https://machinistcharts.com/tap-drill/12-24/"
  },
  {
   "thread": "1/4-20",
   "series": "UNC",
   "major_diameter_in": 0.25,
   "tpi": 20,
   "tap_drill": "#7",
   "tap_drill_mm": 5.11,
   "tap_drill_in": 0.201,
   "thread_percent": 75,
   "url": "https://machinistcharts.com/tap-drill/1-4-20/"
  },
  {
   "thread": "5/16-18",
   "series": "UNC",
   "major_diameter_in": 0.3125,
   "tpi": 18,
   "tap_drill": "F",
   "tap_drill_mm": 6.53,
   "tap_drill_in": 0.257,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/5-16-18/"
  },
  {
   "thread": "3/8-16",
   "series": "UNC",
   "major_diameter_in": 0.375,
   "tpi": 16,
   "tap_drill": "5/16",
   "tap_drill_mm": 7.94,
   "tap_drill_in": 0.3125,
   "thread_percent": 77,
   "url": "https://machinistcharts.com/tap-drill/3-8-16/"
  },
  {
   "thread": "7/16-14",
   "series": "UNC",
   "major_diameter_in": 0.4375,
   "tpi": 14,
   "tap_drill": "U",
   "tap_drill_mm": 9.35,
   "tap_drill_in": 0.368,
   "thread_percent": 75,
   "url": "https://machinistcharts.com/tap-drill/7-16-14/"
  },
  {
   "thread": "1/2-13",
   "series": "UNC",
   "major_diameter_in": 0.5,
   "tpi": 13,
   "tap_drill": "27/64",
   "tap_drill_mm": 10.72,
   "tap_drill_in": 0.4219,
   "thread_percent": 78,
   "url": "https://machinistcharts.com/tap-drill/1-2-13/"
  },
  {
   "thread": "9/16-12",
   "series": "UNC",
   "major_diameter_in": 0.5625,
   "tpi": 12,
   "tap_drill": "31/64",
   "tap_drill_mm": 12.3,
   "tap_drill_in": 0.4844,
   "thread_percent": 72,
   "url": "https://machinistcharts.com/tap-drill/9-16-12/"
  },
  {
   "thread": "5/8-11",
   "series": "UNC",
   "major_diameter_in": 0.625,
   "tpi": 11,
   "tap_drill": "17/32",
   "tap_drill_mm": 13.5,
   "tap_drill_in": 0.5313,
   "thread_percent": 79,
   "url": "https://machinistcharts.com/tap-drill/5-8-11/"
  },
  {
   "thread": "3/4-10",
   "series": "UNC",
   "major_diameter_in": 0.75,
   "tpi": 10,
   "tap_drill": "21/32",
   "tap_drill_mm": 16.67,
   "tap_drill_in": 0.6563,
   "thread_percent": 72,
   "url": "https://machinistcharts.com/tap-drill/3-4-10/"
  },
  {
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 ]
}