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ANSI (Imperial) and ISO Metric Drill Sizes The first column gives the ANSI Number or Letter drill size and the second column gives the exact size in inches. The third column gives the closest available ISO Metric drill size (or fractional inch size) and finally the fourth column then gives the exact size in inches of this drill. Example #31 - The exact size is 0.1200 inches. The closest ISO size is 3.00mm or 0.1181 inches. Number or Letter Size Diameter (Inches)   Nearest Approved Size Diameter (Inches) 80 0.0135   0.35mm 0.0138 79 0.0145   0.38mm 0.0150 78 0.0160   0.40mm 0.0157 77 0.0180   0.45mm 0.0177 76 0.0200   0.50mm 0.0197 75 0.0210   0.52mm 0.0205 74 0.0225   0.58mm 0.0228 73 0.0240   0.60mm 0.0236 72 0.0250   0.65mm 0.0256 71 0.0260   0.65mm 0.0256 70 0.0280   0.70mm 0.0276 69 0.0292   0.75mm 0.0295 68 0.0310   1/32" 0.3120 67 0.0320   0.82mm 0.0323 66 0.0330   0.85mm 0.0335 65 0.0350   0.90mm 0.0354 64 0.0360   0.92mm 0.0362 63 0.0370   0.95mm 0.0374 62 0.0380   0.98mm 0.0386 61 0.0390   1.00mm 0.0394 60 0.0400   1.00mm 0.0394 59 0.0410   1.05mm 0.0413 58 0.0420   1.05mm 0.0413 57 0.0430   1.10mm 0.0433 56 0.0465   3/64" 0.0469 55 0.0520   1.30mm 0.0512 54 0.0550   1.40mm 0.0551 53 0.0595   1.50mm 0.0591 52 0.0635   1.60mm 0.0630 51 0.0670   1.70mm 0.0669 50 0.0700   1.80mm 0.0709 49 0.0730   1.85mm 0.0728 48 0.0760   1.95mm 0.0768 47 0.0785   2.00mm 0.0787 46 0.0810   2.05mm 0.0807 45 0.0820   2.10mm 0.0827 44 0.0860   2.20mm 0.0866 43 0.0890   2.25mm 0.0886 42 0.0935   3/32" 0.0938 41 0.0960   2.45mm 0.0965 40 0.0980   2.50mm 0.0984 39 0.0995   2.55mm 0.1004 38 0.1015   2.60mm 0.1024 37 0.1040   2.65mm 0.1043 36 0.1065   2.70mm 0.1063 35 0.1100   2.80mm 0.1102 34 0.1110   2.80mm 0.1102 33 0.1130   2.85mm 0.1122 32 0.1160   2.95mm 0.1161 31 0.1200   3.00mm 0.1181 30 0.1285   3.30mm 0.1299 29 0.1360   3.50mm 0.1378 28 0.1405   9/64" 0.1406 27 0.1440   3.70mm 0.1457 26 0.1470   3.70mm 0.1457 25 0.1495   3.80mm 0.1496 24 0.1520   3.90mm 0.1535 23 0.1540   3.90mm 0.1535 22 0.1570   4.00mm 0.1575 21 0.1590   4.10mm 0.1614 20 0.1610   4.10mm 0.1614 19 0.1660   4.20mm 0.1654 18 0.1695   4.30mm 0.1693 17 0.1730   4.40mm 0.1732 16 0.1770   4.50mm 0.1772 15 0.1800   4.60mm 0.1811 14 0.1820   4.60mm 0.1811 13 0.1850   4.70mm 0.1850 12 0.1890   4.80mm 0.1890 11 0.1910   4.90mm 0.1929 10 0.1935   4.90mm 0.1929 9 0.1960   5.00mm 0.1969 8 0.1990   5.10mm 0.2008 7 0.2010   5.10mm 0.2008 6 0.2040   5.20mm 0.2047 5 0.2055   5.20mm 0.2047 4 0.2090   5.30mm 0.2087 3 0.2130   5.40mm 0.2126 2 0.2210   5.60mm 0.2205 1 0.2280   5.80mm 0.2283 A 0.2340   15/64" 0.2344 B 0.2380   6.00mm 0.2362 C 0.2420   6.10mm 0.2402 D 0.2460   6.20mm 0.2441 E 0.2500   1/4" 0.2500 F 0.2570   6.50mm 0.2559 G 0.2610   6.60mm 0.2598 H 0.2660   17/64" 0.2656 I 0.2720   6.90mm 0.2717 J 0.2770   7.00mm 0.2756 K 0.2810   9/32" 0.2812 L 0.2900   7.40mm 0.2913 M 0.2950   7.50mm 0.2953 N 0.3020   7.70mm 0.3031 O 0.3160   8.00mm 0.3150 P 0.3230   8.20mm 0.3228 Q 0.3320   8.40mm 0.3307 R 0.3390   8.60mm 0.3386 S 0.3480   8.80mm 0.3465 T 0.3580   9.10mm 0.3583 U 0.3680   9.30mm 0.3661 V 0.3770   3/8" 0.3750 W 0.3860   9.80mm 0.3858 X 0.3970   10.10mm 0.3976 Y 0.4040   10.30mm 0.4055 Z 0.4130   10.50mm 0.4134