Clearance Hole Size Chart for Bolts and Screws (Imperial)
Imperial clearance hole size chart for bolts and screws, including close fit and free fit hole diameters with drill sizes and decimal equivalents
Clearance Hole Size (Imperial) Chart
| Screw Size | Close Fit | Free Fit | ||
|---|---|---|---|---|
| Drill Size | Decimal Equivalent | Drill Size | Decimal Equivalent | |
| 0 | 52 | 0.0635 | 50 | 0.0700 |
| 1 | 48 | 0.0760 | 46 | 0.0810 |
| 2 | 43 | 0.0890 | 41 | 0.0960 |
| 3 | 37 | 0.1040 | 35 | 0.1100 |
| 4 | 32 | 0.1160 | 30 | 0.1285 |
| 5 | 30 | 0.1285 | 29 | 0.1360 |
| 6 | 27 | 0.1440 | 25 | 0.1495 |
| 8 | 18 | 0.1695 | 16 | 0.1770 |
| 10 | 9 | 0.1960 | 7 | 0.2010 |
| 12 | 2 | 0.2210 | 1 | 0.2280 |
| 14 | D | 0.2460 | F | 0.2570 |
| 1/4 | F | 0.2570 | H | 0.2660 |
| 5/16 | P | 0.3230 | Q | 0.3320 |
| 3/8 | W | 0.3860 | X | 0.3970 |
| 7/16 | 29/64 | 0.4531 | 15/32 | 0.4687 |
| 1/2 | 33/64 | 0.5156 | 17/32 | 0.5312 |
About Imperial Clearance Hole Sizes for Bolts and Screws
This Imperial clearance hole size chart provides standardized drill hole dimensions for bolts and screws in Imperial units. It includes recommended close fit holes for precise alignment and free fit holes for easier assembly, along with corresponding drill sizes and decimal equivalents for accurate machining and measurement.
Using accurate Imperial clearance hole dimensions ensures proper screw and bolt seating, alignment, and reliable mechanical performance. This reference is useful for engineers, machinists, and designers working with Imperial fasteners, including:
- Mechanical engineers and product designers creating assemblies in Imperial units.
- Machinists and technicians drilling holes for bolts and screws with precise tolerances.
- Fabricators ensuring correct fit, alignment, and tolerance in mechanical components.
- Assembly and maintenance professionals seeking standardized clearance hole dimensions for reliable fastening.
Key Terms in the Imperial Clearance Hole Chart
- Screw Size: The Imperial designation of the bolt or screw.
- Close Fit: Minimum clearance hole diameter for tight fit and precise alignment.
- Free Fit: Larger clearance hole allowing easier assembly or tolerance for misalignment.
- Drill Size: Standard drill bit used to create the clearance hole.
- Decimal Equivalent: Exact diameter of the drill size in inches for precise measurement and machining.
Referencing this Imperial clearance hole chart for bolts and screws ensures consistent part design, accurate drilling, and proper assembly in Imperial mechanical systems. Correct use of these dimensions improves assembly quality, reduces machining errors, and ensures the correct fit in engineering and manufacturing applications.