METRIC THREAD CUT TAP DRILL SIZES Tap / Thread Size* Basic Major Diameter Tap Drill Size** M1.6 x 0.35 0.063 1.25mm or #55 M2 x 0.4 0.0787 1.60mm or #52 M2.5 x 0.45 0.0984 2.05mm or #46 M3 x 0.5 0.1181 2.50mm or #39 M3.5 x 0.6 0.1378 2.90mm or #32 M4 x 0.7 0.1575 3.30mm or #30 M5 x 0.8 0.1969 4.20mm or #19 M6 x 1 0.2362 5.00mm or #8 M8 x 1.25 0.315 6.80mm or H M8 x 1 0.315 7.00mm or J M10 x 1.5 0.3937 8.50mm or R M10 x 1.25 0.3937 8.80mm or 11/32 M12 x 1.75 0.4724 10.20mm or 13/32 M12 x 1.25 0.4724 10.80mm or 27/64 M14 x 2 0.5512 12.00mm or 15/32 M14 x 1.5 0.5512 12.50mm or 1/2 M16 x 2 0.6299 14.00mm or 35/64 M16 x 1.5 0.6299 14.50mm or 37/64 M18 x 2.5 0.7087 15.50mm or 39/64 M18 x 1.5 0.7087 16.50mm or 21/32 M20 x 2.5 0.7874 17.50mm or 11/16 M20 x 1.5 0.7874 18.50mm or 47/64 M22 x 2.5 0.8661 19.50mm or 49/64 M22 x 1.5 0.8661 20.50mm or 13/16 M24 x 3 0.9449 21.00mm or 53/64 M24 x 2 0.9449 22.00mm or 7/8 M27 x 3 1.063 24.00mm or 15/16 M27 x 2 1.063 25.00mm or 1
*Coarse series shown in red.
** Closest size for 75% theoretical thread.