Complete tap drill size reference for every standard thread. Click any thread for detailed specs, formula, and thread engagement options.
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UNC (Unified National Coarse)
| Thread | Tap Drill | Decimal |
|---|---|---|
| #1-64 UNC | 53 | 0.0595″ |
| #2-56 UNC | 50 | 0.07″ |
| #3-48 UNC | 47 | 0.0785″ |
| #4-40 UNC | 43 | 0.089″ |
| #5-40 UNC | 38 | 0.1015″ |
| #6-32 UNC | 36 | 0.1065″ |
| #8-32 UNC | 29 | 0.136″ |
| #10-24 UNC | 25 | 0.1495″ |
| #12-24 UNC | 16 | 0.177″ |
| 1/4-20 UNC | #7 | 0.201″ |
| 5/16-18 UNC | F | 0.257″ |
| 3/8-16 UNC | 5/16 | 0.3125″ |
| 7/16-14 UNC | U | 0.368″ |
| 1/2-13 UNC | 27/64 | 0.4219″ |
| 9/16-12 UNC | 31/64 | 0.4844″ |
| 5/8-11 UNC | 17/32 | 0.5312″ |
| 3/4-10 UNC | 21/32 | 0.6562″ |
| 7/8-9 UNC | 49/64 | 0.7656″ |
| 1-8 UNC | 7/8 | 0.875″ |
| 1-1/8-7 UNC | 63/64 | 0.9844″ |
| 1-1/4-7 UNC | 1-7/64 | 1.1094″ |
| 1-1/2-6 UNC | 1-11/32 | 1.3438″ |
UNF (Unified National Fine)
| Thread | Tap Drill | Decimal |
|---|---|---|
| #0-80 UNF | 3/64 | 0.0469″ |
| #1-72 UNF | 53 | 0.0595″ |
| #2-64 UNF | 50 | 0.07″ |
| #3-56 UNF | 45 | 0.082″ |
| #4-48 UNF | 42 | 0.0935″ |
| #5-44 UNF | 37 | 0.104″ |
| #6-40 UNF | 33 | 0.113″ |
| #8-36 UNF | 29 | 0.136″ |
| #10-32 UNF | 21 | 0.159″ |
| #12-28 UNF | 14 | 0.182″ |
| 1/4-28 UNF | #3 | 0.213″ |
| 5/16-24 UNF | I | 0.272″ |
| 3/8-24 UNF | Q | 0.332″ |
| 7/16-20 UNF | 25/64 | 0.3906″ |
| 1/2-20 UNF | 29/64 | 0.4531″ |
| 9/16-18 UNF | 33/64 | 0.5156″ |
| 5/8-18 UNF | 37/64 | 0.5781″ |
| 3/4-16 UNF | 11/16 | 0.6875″ |
| 7/8-14 UNF | 13/16 | 0.8125″ |
| 1-12 UNF | 15/16 | 0.9375″ |
| 1-1/8-12 UNF | 1-3/64 | 1.0469″ |
| 1-1/4-12 UNF | 1-11/64 | 1.1719″ |
| 1-1/2-12 UNF | 1-27/64 | 1.4219″ |
Metric ISO (Coarse Pitch)
| Thread | Tap Drill | Decimal |
|---|---|---|
| M1.6×0.35 | 1.25mm | 0.0492″ |
| M2x0.4 | 1.6mm | 0.063″ |
| M2.5×0.45 | 2.05mm | 0.0807″ |
| M3x0.5 | 2.5mm | 0.0984″ |
| M4x0.7 | 3.3mm | 0.1299″ |
| M5x0.8 | 4.2mm | 0.1654″ |
| M6x1.0 | 5.0mm | 0.1969″ |
| M8x1.25 | 6.8mm | 0.2677″ |
| M10x1.5 | 8.5mm | 0.3346″ |
| M12x1.75 | 10.2mm | 0.4016″ |
| M14x2.0 | 12.0mm | 0.4724″ |
| M16x2.0 | 14.0mm | 0.5512″ |
| M18x2.5 | 15.5mm | 0.6102″ |
| M20x2.5 | 17.5mm | 0.689″ |
| M22x2.5 | 19.5mm | 0.7677″ |
| M24x3.0 | 21.0mm | 0.8268″ |
| M27x3.0 | 24.0mm | 0.9449″ |
| M30x3.5 | 26.5mm | 1.0433″ |
Metric ISO (Fine Pitch)
| Thread | Tap Drill | Decimal |
|---|---|---|
| M3x0.35 | 2.65mm | 0.1043″ |
| M4x0.5 | 3.5mm | 0.1378″ |
| M5x0.5 | 4.5mm | 0.1772″ |
| M6x0.75 | 5.25mm | 0.2067″ |
| M7x0.75 | 6.25mm | 0.2461″ |
| M8x0.75 | 7.25mm | 0.2854″ |
| M8x1.0 | 7.0mm | 0.2756″ |
| M10x0.75 | 9.25mm | 0.3642″ |
| M10x1.0 | 9.0mm | 0.3543″ |
| M10x1.25 | 8.8mm | 0.3465″ |
| M12x1.0 | 11.0mm | 0.4331″ |
| M12x1.25 | 10.8mm | 0.4252″ |
| M12x1.5 | 10.5mm | 0.4134″ |
| M14x1.0 | 13.0mm | 0.5118″ |
| M14x1.25 | 12.8mm | 0.5039″ |
| M14x1.5 | 12.5mm | 0.4921″ |
| M16x1.0 | 15.0mm | 0.5906″ |
| M16x1.5 | 14.5mm | 0.5709″ |
| M18x1.0 | 17.0mm | 0.6693″ |
| M18x1.5 | 16.5mm | 0.6496″ |
| M18x2.0 | 16.0mm | 0.6299″ |
| M20x1.0 | 19.0mm | 0.748″ |
| M20x1.5 | 18.5mm | 0.7283″ |
| M20x2.0 | 18.0mm | 0.7087″ |
| M22x1.0 | 21.0mm | 0.8268″ |
| M22x1.5 | 20.5mm | 0.8071″ |
| M22x2.0 | 20.0mm | 0.7874″ |
| M24x1.0 | 23.0mm | 0.9055″ |
| M24x1.5 | 22.5mm | 0.8858″ |
| M24x2.0 | 22.0mm | 0.8661″ |
| M27x1.0 | 26.0mm | 1.0236″ |
| M27x1.5 | 25.5mm | 1.0039″ |
| M27x2.0 | 25.0mm | 0.9843″ |
| M30x1.0 | 29.0mm | 1.1417″ |
| M30x1.5 | 28.5mm | 1.122″ |
| M30x2.0 | 28.0mm | 1.1024″ |
⚠️ Cut Tap vs. Form Tap
Sizes listed are for cut taps at 75% thread. Form taps require a larger hole (2-5% bigger). Check manufacturer data.
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