Tapping Drill Sizes
Tapping drill sizes when pre-drilling for tapped holes. Recommended metric sizes in accordance with DIN 13 and DIN ISO965-1 and Imperial sizes to UNC ASME B1.1
Metric Coarse Sizes
| Tap Size | Drill Size |
|---|---|
| 1.1mm x .25 | .85mm |
| 1.2mm x .25 | .95mm |
| 1.4mm x .3 | 1.1mm |
| 1.3mm x .35 | 1.25mm |
| 1.7mm x .35 | 1.3mm |
| 1.8mm x .35 | 1.45mm |
| 10mm x 1.5 | 8.5mm |
| 11mm x 1.5 | 9.5mm |
| 12mm x 1.5 | 10.5mm |
| 12mm x 1.75 | 10.2mm |
| 14mm x 1 | 13mm |
| 14mm x 2 | 12mm |
| 16mm x 2 | 14mm |
| 18mm x 2.5 | 15.5mm |
| 1mm x .25 | .75mm |
| 2.2mm x .45 | 1.75mm |
| 2.5mm x .45 | 2.05mm |
| 20mm x 2.5 | 17.5mm |
| 22mm x 2.5 | 19.5mm |
| 24mm x 3 | 21mm |
| 27mm x 3 | 24mm |
| 2mm x .4 | 1.6mm |
| 3.5mm x .6 | 2.9mm |
| 30mm x 3.5 | 26.5mm |
| 33mm x 3.5 | 29.5mm |
| 36mm x 4 | 32mm |
| 39mm x 4 | 35mm |
| 3mm x .5 | 2.5mm |
| 4.5mm x .75 | 3.7mm |
| 4mm x .7 | 3.3mm |
| 5mm x .8 | 4.2mm |
| 6mm x 1 | 5mm |
| 7mm x 1 | 6mm |
| 8mm x 1.25 | 6.8mm |
| 9mm x 1.25 | 7.8mm |
Metric Fine Sizes
| Tap Size | Drill Size |
|---|---|
| 10mm x .75 | 9.25mm |
| 10mm x 1 | 9mm |
| 10mm x 1.25 | 8.8mm |
| 11mm x 1 | 10mm |
| 12mm x .75 | 11.25mm |
| 12mm x 1 | 11mm |
| 14mm x 1.25 | 12.8mm |
| 14mm x 1.5 | 12.5mm |
| 16mm x 1 | 15mm |
| 16mm x 1.5 | 14.5mm |
| 18mm x 1 | 17mm |
| 18mm x 2 | 16mm |
| 20mm x 1 | 19mm |
| 20mm x 1.5 | 18.5mm |
| 20mm x 2 | 18mm |
| 22mm x 1 | 21mm |
| 22mm x 1.5 | 20.5mm |
| 22mm x 2 | 20m |
| 24mm x 1.5 | 22.5mm |
| 24mm x 2 | 22mm |
| 26mm x 1.5 | 24.5mm |
| 27mm x 1.5 | 25.5mm |
| 27mm x 2 | 25mm |
| 28mm x 1.5 | 26.5mm |
| 30mm x 1.5 | 28.5mm |
| 30mm x 2 | 28mm |
| 33mm x 2 | 31mm |
| 36mm x 3 | 33mm |
| 39mm x 3 | 36mm |
| 4mm x .35 | 3.6mm |
| 4mm x .5 | 3.5mm |
| 5mm x .5 | 4.5mm |
| 6mm x .5 | 5.5mm |
| 6mm x .75 | 5.25mm |
| 7mm x .75 | 6.25mm |
| 8mm x .5 | 7.5mm |
| 8mm x .75 | 7.25mm |
| 9mm x 1 | 8mm |
INCH SIZES - NATIONAL COARSE
| Tap Size | Drill Size |
|---|---|
| #1-64 | #53 |
| #2-56 | #51 |
| #3-48 | 5/64" |
| #4-40 | #43 |
| #5-40 | #38 |
| #6-32 | #36 |
| #8-32 | #29 |
| #10-24 | #25 |
| #12-24 | #17 |
| 1/4-20 | #7 |
| 5/16-18 | F |
| 3/8-16 | 5/16 |
| 7/16-14 | U |
| 1/2-13 | 27/64 |
| 9/16-12 | 31/64 |
| 5/8-11 | 17/32 |
| 3/4-10 | 21/32 |
| 7/8-9 | 49/64 |
| 1"-8 | 7/8 |
| 1-1/8-7 | 63/64 |
| 1-1/4-7 | 1-7/64 |
| 1-1/2-6 | 1-11/32 |
| 1-3/4-5 | 1-35/64 |
| 2"-4-1/2 | 1-25/32 |
INCH SIZES - NATIONAL FINE
| Tap Size | Drill Size |
|---|---|
| #0-80 | 3/64" |
| #1-72 | #53 |
| #2-64 | #50 |
| #3-56 | #46 |
| #4-48 | #42 |
| #5-44 | #37 |
| #6-40 | #33 |
| #8-36 | #29 |
| #10-32 | #21 |
| #12-28 | #15 |
| 1/4-28 | #3 |
| 5/16-24 | I |
| 3/8-24 | Q |
| 7/16-20 | W |
| 1/2-20 | 29/64 |
| 9/16-18 | 33/64 |
| 5/8-18 | 37/64 |
| 3/4-16 | 11/16 |
| 7/8-14 | 13/16 |
| 1"-14 | 15/16 |
| 1-1/8-12 | 1-3/64 |
| 1-1/4-12 | 1-11/64 |
| 1-1/2-12 | 1-27/64 |
| 1-3/4-12 | 1-43/64 |
| 2"-12 | 1-59/64 |
