Calculators
Clearance Hole Calculator
Standard metric clearance holes (ISO 273) for a bolt through a part — close, normal, and loose fits — so the fastener passes through without binding.
Last verified: 2026-07-09
A clearance hole lets a bolt pass through the top part and thread into the one below. Pick the bolt size and how much clearance you want — close for precise location, normal for general use, loose for easy assembly.
Fit
Clearance drill (normal)
6.6mm
| Size | Close | Normal | Loose |
|---|---|---|---|
| M3 | 3.2 | 3.4 | 3.6 |
| M4 | 4.3 | 4.5 | 4.8 |
| M5 | 5.3 | 5.5 | 5.8 |
| M6 | 6.4 | 6.6 | 7 |
| M8 | 8.4 | 9 | 10 |
| M10 | 10.5 | 11 | 12 |
| M12 | 13 | 13.5 | 14.5 |
| M16 | 17 | 17.5 | 18.5 |
| M20 | 21 | 22 | 24 |
Standard ISO 273 metric clearance holes. Choose Close for precise location, Normal for general use, Loose for easy assembly / misalignment tolerance.
Frequently asked
- Close, normal, or loose?
- Close minimizes play (accurate location), normal is the general-purpose default, and loose gives the most room for misalignment or thermal movement. All three are standard ISO 273 sizes.
- Do you have inch clearance holes?
- This tool uses the metric ISO 273 standard. For inch fasteners, consult ASME B18.2.8 clearance-hole values (a verified inch table is on the roadmap).
Sources
- ISO 273 — Fasteners: clearance holes for bolts and screws (metric)