Metric coarse and fine and UNC/UNF threads with their pitch, the tap drill and the close, normal and loose clearance holes.
| Designation | Series | Major dia. (mm) | Pitch (mm) | Tap drill | Clearance hole (close / normal / loose) |
|---|---|---|---|---|---|
| #1-64 UNC | UNC (coarse) | 1.85 | 64 TPI | #53 (1.51 mm) | #46 / #43 / #37 |
| #2-56 UNC | UNC (coarse) | 2.18 | 56 TPI | #50 (1.78 mm) | 3/32″ / #38 / #32 |
| #3-48 UNC | UNC (coarse) | 2.51 | 48 TPI | #47 (1.99 mm) | #36 / #32 / #30 |
| #4-40 UNC | UNC (coarse) | 2.84 | 40 TPI | #43 (2.26 mm) | #31 / #30 / #27 |
| #5-40 UNC | UNC (coarse) | 3.17 | 40 TPI | #38 (2.58 mm) | 9/64″ / 5/32″ / 11/64″ |
| #6-32 UNC | UNC (coarse) | 3.51 | 32 TPI | #36 (2.71 mm) | #23 / #18 / #13 |
| #8-32 UNC | UNC (coarse) | 4.17 | 32 TPI | #29 (3.45 mm) | #15 / #9 / #3 |
| #10-24 UNC | UNC (coarse) | 4.83 | 24 TPI | #25 (3.8 mm) | #5 / #2 / B |
| #12-24 UNC | UNC (coarse) | 5.49 | 24 TPI | #16 (4.5 mm) | — |
| 1/4″-20 UNC | UNC (coarse) | 6.35 | 20 TPI | #7 (5.11 mm) | 17/64″ / 9/32″ / 19/64″ |
| 5/16″-18 UNC | UNC (coarse) | 7.94 | 18 TPI | F (6.53 mm) | 21/64″ / 11/32″ / 23/64″ |
| 3/8″-16 UNC | UNC (coarse) | 9.52 | 16 TPI | 5/16″ (7.94 mm) | 25/64″ / 13/32″ / 27/64″ |
| 7/16″-14 UNC | UNC (coarse) | 11.11 | 14 TPI | U (9.35 mm) | 29/64″ / 15/32″ / 31/64″ |
| 1/2″-13 UNC | UNC (coarse) | 12.7 | 13 TPI | 27/64″ (10.72 mm) | 17/32″ / 9/16″ / 39/64″ |
| 9/16″-12 UNC | UNC (coarse) | 14.29 | 12 TPI | 31/64″ (12.3 mm) | — |
| 5/8″-11 UNC | UNC (coarse) | 15.88 | 11 TPI | 17/32″ (13.49 mm) | 21/32″ / 11/16″ / 47/64″ |
| 3/4″-10 UNC | UNC (coarse) | 19.05 | 10 TPI | 21/32″ (16.67 mm) | 25/32″ / 13/16″ / 29/32″ |
| 7/8″-9 UNC | UNC (coarse) | 22.22 | 9 TPI | 49/64″ (19.45 mm) | 29/32″ / 15/16″ / 1-1/32″ |
| 1″-8 UNC | UNC (coarse) | 25.4 | 8 TPI | 7/8″ (22.22 mm) | 1-1/32″ / 1-3/32″ / 1-5/32″ |
| #0-80 UNF | UNF (fine) | 1.52 | 80 TPI | 3/64″ (1.19 mm) | #51 / #48 / 3/32″ |
| #1-72 UNF | UNF (fine) | 1.85 | 72 TPI | #53 (1.51 mm) | #46 / #43 / #37 |
| #2-64 UNF | UNF (fine) | 2.18 | 64 TPI | #50 (1.78 mm) | 3/32″ / #38 / #32 |
| #3-56 UNF | UNF (fine) | 2.51 | 56 TPI | #45 (2.08 mm) | #36 / #32 / #30 |
| #4-48 UNF | UNF (fine) | 2.84 | 48 TPI | #42 (2.37 mm) | #31 / #30 / #27 |
| #5-44 UNF | UNF (fine) | 3.17 | 44 TPI | #37 (2.64 mm) | 9/64″ / 5/32″ / 11/64″ |
| #6-40 UNF | UNF (fine) | 3.51 | 40 TPI | #33 (2.87 mm) | #23 / #18 / #13 |
| #8-36 UNF | UNF (fine) | 4.17 | 36 TPI | #29 (3.45 mm) | #15 / #9 / #3 |
| #10-32 UNF | UNF (fine) | 4.83 | 32 TPI | #21 (4.04 mm) | #5 / #2 / B |
| #12-28 UNF | UNF (fine) | 5.49 | 28 TPI | #14 (4.62 mm) | — |
| 1/4″-28 UNF | UNF (fine) | 6.35 | 28 TPI | #3 (5.41 mm) | 17/64″ / 9/32″ / 19/64″ |
| 5/16″-24 UNF | UNF (fine) | 7.94 | 24 TPI | I (6.91 mm) | 21/64″ / 11/32″ / 23/64″ |
| 3/8″-24 UNF | UNF (fine) | 9.52 | 24 TPI | Q (8.43 mm) | 25/64″ / 13/32″ / 27/64″ |
| 7/16″-20 UNF | UNF (fine) | 11.11 | 20 TPI | 25/64″ (9.92 mm) | 29/64″ / 15/32″ / 31/64″ |
| 1/2″-20 UNF | UNF (fine) | 12.7 | 20 TPI | 29/64″ (11.51 mm) | 17/32″ / 9/16″ / 39/64″ |
| 9/16″-18 UNF | UNF (fine) | 14.29 | 18 TPI | 33/64″ (13.1 mm) | — |
| 5/8″-18 UNF | UNF (fine) | 15.88 | 18 TPI | 37/64″ (14.68 mm) | 21/32″ / 11/16″ / 47/64″ |
| 3/4″-16 UNF | UNF (fine) | 19.05 | 16 TPI | 11/16″ (17.46 mm) | 25/32″ / 13/16″ / 29/32″ |
| 7/8″-14 UNF | UNF (fine) | 22.22 | 14 TPI | 13/16″ (20.64 mm) | 29/32″ / 15/16″ / 1-1/32″ |
| 1″-12 UNF | UNF (fine) | 25.4 | 12 TPI | 59/64″ (23.42 mm) | 1-1/32″ / 1-3/32″ / 1-5/32″ |
| M1.6 × 0.35 | Metric coarse | 1.6 | 0.35 | 1.25 mm ✓ | 1.7 mm / 1.8 mm / 2 mm |
| M2 × 0.4 | Metric coarse | 2 | 0.4 | 1.6 mm ✓ | 2.2 mm / 2.4 mm / 2.6 mm |
| M2.5 × 0.45 | Metric coarse | 2.5 | 0.45 | 2.05 mm ✓ | 2.7 mm / 2.9 mm / 3.1 mm |
| M3 × 0.5 | Metric coarse | 3 | 0.5 ✓ | 2.5 mm ✓ | 3.2 mm / 3.4 mm / 3.6 mm |
| M3.5 × 0.6 | Metric coarse | 3.5 | 0.6 | 2.9 mm ✓ | 3.7 mm / 3.9 mm / 4.2 mm |
| M4 × 0.7 | Metric coarse | 4 | 0.7 ✓ | 3.3 mm ✓ | 4.3 mm / 4.5 mm / 4.8 mm |
| M5 × 0.8 | Metric coarse | 5 | 0.8 ✓ | 4.2 mm ✓ | 5.3 mm / 5.5 mm / 5.8 mm |
| M6 × 1 | Metric coarse | 6 | 1 ✓ | 5 mm ✓ | 6.4 mm / 6.6 mm / 7 mm |
| M8 × 1.25 | Metric coarse | 8 | 1.25 ✓ | 6.8 mm ✓ | 8.4 mm / 9 mm / 10 mm |
| M10 × 1.5 | Metric coarse | 10 | 1.5 ✓ | 8.5 mm ✓ | 10.5 mm / 11 mm / 12 mm |
| M12 × 1.75 | Metric coarse | 12 | 1.75 ✓ | 10.2 mm ✓ | 13 mm / 13.5 mm / 14.5 mm |
| M14 × 2 | Metric coarse | 14 | 2 ✓ | 12 mm ✓ | 15 mm / 15.5 mm / 16.5 mm |
| M16 × 2 | Metric coarse | 16 | 2 ✓ | 14 mm ✓ | 17 mm / 17.5 mm / 18.5 mm |
| M18 × 2.5 | Metric coarse | 18 | 2.5 | 15.5 mm ✓ | 19 mm / 20 mm / 21 mm |
| M20 × 2.5 | Metric coarse | 20 | 2.5 ✓ | 17.5 mm ✓ | 21 mm / 22 mm / 24 mm |
| M22 × 2.5 | Metric coarse | 22 | 2.5 | 19.5 mm ✓ | 23 mm / 24 mm / 26 mm |
| M24 × 3 | Metric coarse | 24 | 3 ✓ | 21 mm ✓ | 25 mm / 26 mm / 28 mm |
| M8 × 1 | Metric fine | 8 | 1 | 7 mm ✓ | 8.4 mm / 9 mm / 10 mm |
| M10 × 1 | Metric fine | 10 | 1 | 9 mm ✓ | 10.5 mm / 11 mm / 12 mm |
| M10 × 1.25 | Metric fine | 10 | 1.25 | 8.8 mm ✓ | 10.5 mm / 11 mm / 12 mm |
| M12 × 1.25 | Metric fine | 12 | 1.25 | 10.8 mm ✓ | 13 mm / 13.5 mm / 14.5 mm |
| M12 × 1.5 | Metric fine | 12 | 1.5 | 10.5 mm ✓ | 13 mm / 13.5 mm / 14.5 mm |
| M14 × 1.5 | Metric fine | 14 | 1.5 | 12.5 mm ✓ | 15 mm / 15.5 mm / 16.5 mm |
| M16 × 1.5 | Metric fine | 16 | 1.5 | 14.5 mm ✓ | 17 mm / 17.5 mm / 18.5 mm |
| M18 × 1.5 | Metric fine | 18 | 1.5 | 16.5 mm ✓ | 19 mm / 20 mm / 21 mm |
| M20 × 1.5 | Metric fine | 20 | 1.5 | 18.5 mm ✓ | 21 mm / 22 mm / 24 mm |
From BenchReference (ASME B1.1, ISO 261/724, ISO 273, ASME B18.2.8; ~75 % thread tap drills per Machinery's Handbook). ✓ = coarse pitch per ISO 261 or metric tap drill = D − P.
Source: BenchReference physical standards dataset (benchreference.com/data/), CC BY 4.0; values from the standards cited at benchreference.com/sources/. ↗
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