Metric and imperial tap drill lookup for fabrication drawings
Use this chart to check common tap drills, decimal equivalents, and clearance holes before sending a bracket, panel, enclosure, or fabricated assembly to FortiFab for review.
Tap drill and clearance lookup
17 of 17 sizes
| Tap size | Thread | Tap drill | Decimal | Metric equivalent | Close clearance | Free clearance | Typical use |
|---|---|---|---|---|---|---|---|
| M3 × 0.5 | Coarse | 2.5 mm | 0.0984 in | 2.5 mm | 3.2 mm | 3.4 mm | Small covers, brackets, and light hardware |
| M4 × 0.7 | Coarse | 3.3 mm | 0.1299 in | 3.3 mm | 4.3 mm | 4.5 mm | Common small machine screw size |
| M5 × 0.8 | Coarse | 4.2 mm | 0.1654 in | 4.2 mm | 5.3 mm | 5.5 mm | Panels, covers, and small mounts |
| M6 × 1.0 | Coarse | 5.0 mm | 0.1969 in | 5.0 mm | 6.4 mm | 6.6 mm | Frequent enclosure and bracket fastener |
| M8 × 1.25 | Coarse | 6.8 mm | 0.2677 in | 6.8 mm | 8.4 mm | 9.0 mm | Heavier brackets and equipment mounts |
| M10 × 1.5 | Coarse | 8.5 mm | 0.3346 in | 8.5 mm | 10.5 mm | 11.0 mm | Frames, guards, and heavier assemblies |
| M12 × 1.75 | Coarse | 10.2 mm | 0.4016 in | 10.2 mm | 13.0 mm | 13.5 mm | Large mounting points and structural hardware |
| M16 × 2.0 | Coarse | 14.0 mm | 0.5512 in | 14.0 mm | 17.0 mm | 17.5 mm | Heavy industrial mounting hardware |
| #6-32 UNC | Coarse | #36 | 0.1065 in | 2.71 mm | #27 | #25 | Small covers and electronics-style hardware |
| #8-32 UNC | Coarse | #29 | 0.1360 in | 3.45 mm | #18 | #16 | Light panels and brackets |
| #10-24 UNC | Coarse | #25 | 0.1495 in | 3.80 mm | #9 | #7 | General sheet-metal hardware |
| #10-32 UNF | Fine | #21 | 0.1590 in | 4.04 mm | #9 | #7 | Fine-thread hardware where vibration matters |
| 1/4-20 UNC | Coarse | #7 | 0.2010 in | 5.11 mm | F | H | Common bracket and enclosure fastener |
| 1/4-28 UNF | Fine | #3 | 0.2130 in | 5.41 mm | F | H | Fine-thread quarter-inch hardware |
| 5/16-18 UNC | Coarse | F | 0.2570 in | 6.53 mm | P | Q | Medium-duty mounting points |
| 3/8-16 UNC | Coarse | 5/16 in | 0.3125 in | 7.94 mm | 25/64 in | 13/32 in | Equipment mounts and heavier guards |
| 1/2-13 UNC | Coarse | 27/64 in | 0.4219 in | 10.72 mm | 17/32 in | 9/16 in | Large industrial mounts |
Reference values are common shop-planning sizes. Confirm the final hole callout, thread class, depth, fastener, and tolerance requirements on the drawing.
Tap drill hardware guide
Choose tap, clearance, and hardware notes before quoting panels
Use the tap drill chart to clarify threaded-hole and clearance-hole callouts before sending FortiFab drawings. Tapped holes, PEM hardware, countersinks, and slots need material, thickness, edge distance, plating, and bend-proximity review.
Common searches
- tap drill chart
- clearance hole chart
- metric tap drill size
- imperial tap drill size
Best buyer use cases
- Panels and brackets with tapped holes
- Enclosures with PEM studs, nuts, or hardware inserts
- Quote notes for clearance holes, countersinks, and fastener patterns
Ready to turn this into a reviewed fabrication quote?
Send drawings, sketches, material, thickness, finish, quantity, and any fit-up requirements so FortiFab can review manufacturability.
Tap drill chart FAQs
Common questions about using tap drill and clearance-hole references in fabrication RFQs.