M3 clearance hole size (medium fit)
A practical medium clearance hole for an M3 shank is about 3.4 mm for slip fit in sheet and plate layouts.
Tight or close fits use smaller pilots; oversized holes add play and lower bearing on the bolt shoulder.
Compare the hub bolt size chart, then open screw size conversion if you must align metric holes with inch hardware bins.
These values target common machine-design slip fits; verify against ISO 273 or your assembly drawing tolerance class.
M3 clearance hole
| Fit intent | Clearance diameter |
|---|---|
| Nominal bolt | M3 |
| Medium slip (typical) | 3.4 mm |
| Notes | Deburr; add positional tolerance for stacked plates. |
When clearance changes
Paint thickness, thermal growth, or sleeve bushings can require opening holes slightly; never shrink below tap-drill sizes on threaded bosses.
M3 links and tools
Open the bolt size chart (M3) for hex, pitch, and tap drill in one hub table.
Use tap drill size when pitch differs from coarse or you need a quick recalculation.
Run the thread identifier after you measure major diameter and pitch on a sample thread.
Compare stocked inch hardware with screw size conversion when you cross-shop bins.
Convert pitch units with the thread pitch chart tool when drawings mix mm and TPI.
Review metric vs unc thread naming before you mix UNC taps with metric holes.
Neighbor metric hub: bolt size chart (M4) for the next larger shank.