Below is a table for metric tap drill sizes. It covers both threaded holes (when you are cutting thread) and clearance holes (when you are simply placing a bolt through a hole).
Metric Tap Drill Chart | ||||||
Tap size | Major Dia (mm) |
Threads per |
Tap Drill (mm) |
Tap Drill (inch) |
Clearance Hole (mm) |
Clearance Hole (inch) |
M1.6×0.35 | 1.6 | 0.35 | 1.25 | #55 | 1.8 | #49 |
M2x0.4 | 2.0 | 0.40 | 1.60 | #52 | 2.4 | #41 |
M2.5×0.45 | 2.5 | 0.45 | 2.05 | #46 | 2.9 | #32 |
M3x.05 | 3.0 | 0.50 | 2.50 | #39 | 3.4 | #29 |
M3.5×0.6 | 3.5 | 0.60 | 2.90 | #32 | 3.9 | #23 |
M4x0.7 | 4.0 | 0.70 | 3.30 | #30 | 4.5 | #16 |
M5x0.8 | 5.0 | 0.80 | 4.20 | #19 | 5.5 | 7/32 |
M6x1 | 6.0 | 1.00 | 5.0 | #8 | 6.6 | G |
M8x1.25 | 8.0 | 1.25 | 6.8 | H | 9.0 | T |
M8x1 | 8.0 | 1.00 | 7.0 | J | 9.0 | T |
M10x1.5 | 10.0 | 1.50 | 8.5> | R | 12.0 | 31/64 |
M10x1.25 | 10.0 | 1.25 | 8.8 | 11/32 | 12.0 | 31/64 |
M12x1.75 | 12.0 | 1.75 | 10.2 | 13/32 | 14.0 | 35/64 |
M12x1.25 | 12.0 | 1.25 | 10.8 | 27/64 | 14.0 | 35/64 |
M14x2 | 14.0 | 2.00 | 12.0 | 15/32 | 16.0 | 5/8 |
M14x1.5 | 14.0 | 1.5 | 12.5 | 1/2 | 16.0 | 5/8 |
M16x2 | 16.0 | 2.00 | 14.0 | 35/64 | 18.0 | 45/64 |
M16x1.5 | 16.0 | 1.50 | 14.5 | 37/64 | 18.0 | 45/64 |
M18x2.5 | 18.0 | 2.50 | 15.5 | 39/64 | 20.0 | 51/64 |
M18x1.5 | 18.0 | 1.50 | 16.5 | 21/32 | 20.0 | 51/64 |
M20x2.5 | 20.0 | 2.50 | 17.5 | 11/16 | 22.0 | 7/8 |
M20x1.5 | 20.0 | 1.50 | 18.5 | 47/64 | 22.0 | 7/8 |
M22x2.5 | 22.0 | 2.50 | 19.5 | 49/64 | 25.0 | 1 |
M22x1.5 | 22.0 | 1.50 | 20.5 | 13/16 | 25.0 | 1 |
M24x3 | 24.0 | 3.00 | 21.0 | 53/64 | 27.0 | 1-5/64 |
M24x2 | 24.0 | 2.00 | 22.0 | 7/8 | 27.0 | 1-5/64 |
M27x3 | 27.0 | 3.00 | 24.0 | 15/16 | 30.0 | 1-3/16 |
M27x2 | 27.0 | 2.0 | 25.0 | 1 | 30.0 | 1-3/16 |
Standard UNC Tap Drill Sizes
Standard UNF Tap Drill Sizes
Standard NPT Tap Drill Sizes