The tap drill for every UNC, UNF and metric coarse and fine thread, with its decimal size and percent of thread, and the close and free fit clearance holes. Print it for the drill press.
| Thread | Tap drillabout 75% thread | % thread | Clearance holeclose fit | Clearance holefree fit |
|---|---|---|---|---|
| #0-80UNF | 3/640.0469 | 81% | #520.0635 | #500.0700 |
| #1-64UNC | #530.0595 | 67% | #480.0760 | #460.0810 |
| #1-72UNF | #530.0595 | 75% | #480.0760 | #460.0810 |
| #2-56UNC | #500.0700 | 69% | #430.0890 | #410.0960 |
| #2-64UNF | #500.0700 | 79% | #430.0890 | #410.0960 |
| #3-48UNC | #470.0785 | 76% | #370.1040 | #350.1100 |
| #3-56UNF | #450.0820 | 73% | #370.1040 | #350.1100 |
| #4-40UNC | #430.0890 | 71% | #320.1160 | #300.1285 |
| #4-48UNF | #420.0935 | 68% | #320.1160 | #300.1285 |
| #5-40UNC | #380.1015 | 72% | #300.1285 | #290.1360 |
| #5-44UNF | #370.1040 | 71% | #300.1285 | #290.1360 |
| #6-32UNC | #360.1065 | 78% | #270.1440 | #250.1495 |
| #6-40UNF | #330.1130 | 77% | #270.1440 | #250.1495 |
| #8-32UNC | #290.1360 | 69% | #180.1695 | #160.1770 |
| #8-36UNF | #290.1360 | 78% | #180.1695 | #160.1770 |
| #10-24UNC | #250.1495 | 75% | #90.1960 | #70.2010 |
| #10-32UNF | #210.1590 | 76% | #90.1960 | #70.2010 |
| #12-24UNC | #160.1770 | 72% | #20.2210 | #10.2280 |
| #12-28UNF | #140.1820 | 73% | #20.2210 | #10.2280 |
| 1/4-20UNC | #70.2010 | 75% | F0.2570 | H0.2660 |
| 1/4-28UNF | #30.2130 | 80% | F0.2570 | H0.2660 |
| 5/16-18UNC | F0.2570 | 77% | P0.3230 | Q0.3320 |
| 5/16-24UNF | I0.2720 | 75% | P0.3230 | Q0.3320 |
| 3/8-16UNC | 5/160.3125 | 77% | W0.3860 | X0.3970 |
| 3/8-24UNF | Q0.3320 | 79% | W0.3860 | X0.3970 |
| 7/16-14UNC | U0.3680 | 75% | 29/640.4531 | 15/320.4688 |
| 7/16-20UNF | 25/640.3906 | 72% | 29/640.4531 | 15/320.4688 |
| 1/2-13UNC | 27/640.4219 | 78% | 33/640.5156 | 17/320.5313 |
| 1/2-20UNF | 29/640.4531 | 72% | 33/640.5156 | 17/320.5313 |
| 9/16-12UNC | 31/640.4844 | 72% | 37/640.5781 | 19/320.5938 |
| 9/16-18UNF | 33/640.5156 | 65% | 37/640.5781 | 19/320.5938 |
| 5/8-11UNC | 17/320.5313 | 79% | 41/640.6406 | 21/320.6563 |
| 5/8-18UNF | 37/640.5781 | 65% | 41/640.6406 | 21/320.6563 |
| 3/4-10UNC | 21/320.6563 | 72% | 49/640.7656 | 25/320.7813 |
| 3/4-16UNF | 11/160.6875 | 77% | 49/640.7656 | 25/320.7813 |
| 7/8-9UNC | 49/640.7656 | 76% | 57/640.8906 | 29/320.9063 |
| 7/8-14UNF | 13/160.8125 | 67% | 57/640.8906 | 29/320.9063 |
| 1-8UNC | 7/80.8750 | 77% | 1-1/641.0156 | 1-1/321.0313 |
| 1-12UNF | 59/640.9219 | 72% | 1-1/641.0156 | 1-1/321.0313 |
| 1-1/8-7UNC | 63/640.9844 | 76% | — | — |
| 1-1/8-12UNF | 1-3/641.0469 | 72% | — | — |
| 1-1/4-7UNC | 1-7/641.1094 | 76% | — | — |
| 1-1/4-12UNF | 1-11/641.1719 | 72% | — | — |
| 1-3/8-6UNC | 1-7/321.2188 | 72% | — | — |
| 1-3/8-12UNF | 1-19/641.2969 | 72% | — | — |
| 1-1/2-6UNC | 1-11/321.3438 | 72% | — | — |
| 1-1/2-12UNF | 1-27/641.4219 | 72% | — | — |
| 1-3/4-5UNC | 1-9/161.5625 | 72% | — | — |
| 2-4.5UNC | 1-25/321.7813 | 76% | — | — |
Tap drills for cutting taps, the drill nearest 75% thread. Clearance holes are listed to 1 in. Click a thread for its limits of size and measurement over wires.
| Thread | Tap drillmm | % thread | Clearance holeclose, mm | Clearance holenormal, mm |
|---|---|---|---|---|
| M1.6 × 0.35coarse | 1.25 | 77% | 1.7 | 1.8 |
| M2 × 0.4coarse | 1.6 | 77% | 2.2 | 2.4 |
| M2.5 × 0.45coarse | 2.05 | 77% | 2.7 | 2.9 |
| M3 × 0.5coarse | 2.5 | 77% | 3.2 | 3.4 |
| M3.5 × 0.6coarse | 2.9 | 77% | 3.7 | 3.9 |
| M4 × 0.7coarse | 3.3 | 77% | 4.3 | 4.5 |
| M5 × 0.8coarse | 4.2 | 77% | 5.3 | 5.5 |
| M6 × 1coarse | 5 | 77% | 6.4 | 6.6 |
| M8 × 1.25coarse | 6.8 | 74% | 8.4 | 9 |
| M8 × 1fine | 7 | 77% | 8.4 | 9 |
| M10 × 1.5coarse | 8.5 | 77% | 10.5 | 11 |
| M10 × 1fine | 9 | 77% | 10.5 | 11 |
| M10 × 1.25fine | 8.8 | 74% | 10.5 | 11 |
| M12 × 1.75coarse | 10.2 | 79% | 13 | 13.5 |
| M12 × 1.25fine | 10.8 | 74% | 13 | 13.5 |
| M12 × 1.5fine | 10.5 | 77% | 13 | 13.5 |
| M14 × 2coarse | 12 | 77% | 15 | 15.5 |
| M14 × 1.5fine | 12.5 | 77% | 15 | 15.5 |
| M16 × 2coarse | 14 | 77% | 17 | 17.5 |
| M16 × 1.5fine | 14.5 | 77% | 17 | 17.5 |
| M18 × 2.5coarse | 15.5 | 77% | 19 | 20 |
| M18 × 1.5fine | 16.5 | 77% | 19 | 20 |
| M20 × 2.5coarse | 17.5 | 77% | 21 | 22 |
| M20 × 1.5fine | 18.5 | 77% | 21 | 22 |
| M20 × 2fine | 18 | 77% | 21 | 22 |
| M22 × 2.5coarse | 19.5 | 77% | 23 | 24 |
| M22 × 1.5fine | 20.5 | 77% | 23 | 24 |
| M24 × 3coarse | 21 | 77% | 25 | 26 |
| M24 × 2fine | 22 | 77% | 25 | 26 |
| M27 × 3coarse | 24 | 77% | 28 | 30 |
| M27 × 2fine | 25 | 77% | 28 | 30 |
| M30 × 3.5coarse | 26.5 | 77% | 31 | 33 |
| M30 × 2fine | 28 | 77% | 31 | 33 |
| M33 × 3.5coarse | 29.5 | 77% | 34 | 36 |
| M36 × 4coarse | 32 | 77% | 37 | 39 |
| M36 × 3fine | 33 | 77% | 37 | 39 |
| M42 × 4.5coarse | 37.5 | 77% | 43 | 45 |
| M48 × 5coarse | 43 | 77% | 50 | 52 |
Tap drills for cutting taps, as the charts list them (about the major diameter less the pitch). Clearance holes are ISO 273, close and normal (medium) series. Click a thread for its limits of size and measurement over wires.
Less thread (60 to 65%) taps easier and breaks fewer taps in tough material, with little loss of strength; soft materials and thin parts want more.
Made by Pylvos, job tracking for small machine shops. This chart, a thread calculator, speeds and feeds, bar yield and more are built into the app, next to your jobs, prints and certs.
Try the live demo →Percent of thread is how much of the full thread depth the tap cuts. For a 60° thread, the drill for a given percentage is drill = major diameter − (percent ÷ 100) × 1.299 × pitch, where the pitch is 1 ÷ threads per inch. The inch chart gives the number, letter or fraction drill nearest 75%, with the percentage that drill really gives. The metric chart gives the drill sizes the standard charts list, which are close to the major diameter less the pitch.
The same formula is behind the calculator above, for any diameter, pitch and percentage. For the limits of size of a thread, its minor and pitch diameters and the measurement over wires, use the thread calculator.
The chart is for cutting taps. Form (roll) taps push the metal instead of cutting it and need a larger drill: use the tap maker's chart. Where a drawing controls the minor diameter, check the drill against its limits in the thread calculator.
A #7 drill (0.201 in), about 75% thread. For 1/4-28, a #3 (0.213 in). For a 10-32, a #21 (0.159 in); for a 10-24, a #25 (0.1495 in).
75% is the usual figure and what this chart gives. A thread cut to 75% is nearly as strong as a full thread, and tapping torque climbs quickly above that. In stainless, titanium and other tough materials, or in deep holes, 60 to 65% taps much more easily with little loss of strength. Soft materials and thin parts want more.
A close fit hole leaves little play, for where the screw helps locate the part. A free fit hole leaves more, so the screw still goes in when hole positions are a little off between two parts. For metric screws, ISO 273 calls these the fine and medium series.
Major diameter less the pitch: an M6 × 1 takes a 5 mm drill, an M8 × 1.25 a 6.8 mm, an M10 × 1.5 an 8.5 mm. That gives about 77% thread.
Pylvos is job tracking for small machine shops: a board everyone can see, prints and certs on every job, and these charts built in. Runs on a PC you already have. Free for up to 3 people.