4 mm Drill Bit Size
A 4 mm drill bit is 0.1575 inches. The nearest common fractional drill bit is 5/32 inch, which measures 0.1563 inches or 3.97 mm.
Quick Answer
Decimal
0.1575 in
Metric
4.00 mm
Closest
5/32 inch
4 mm Drill Bit Equivalent Chart
| Size | Decimal Inches | Metric | Note |
|---|---|---|---|
| 4 mm | 0.1575 in | 4.00 mm | Exact size |
| 5/32 inch | 0.1563 in | 3.97 mm | Closest common fractional size |
| #21 | 0.1590 in | 4.04 mm | Nearby numbered drill size |
| 9/64 inch | 0.1406 in | 3.57 mm | Undersized alternative |
Common Uses
Pilot holes for medium screws, light anchors, and metric fasteners.
Exact vs Nearest Size
Choose the exact bit for threads, tight hardware fits, dowels, and precision layouts. Use the nearest common equivalent only for rough pilot holes, clearance holes, or material removal where a slight difference is acceptable.
4 mm Drill Bit FAQ
What are the inch and metric dimensions for 4 mm?
4 mm drill bit measures 0.1575 in and 4.00 mm.
What is the closest common equivalent to 4 mm?
5/32 inch is the closest common equivalent listed here. It measures 0.1563 in or 3.97 mm.
Can I substitute another bit for 4 mm?
Use the exact bit size for tap drilling, precision holes, dowels, and manufacturer-specified hardware. A nearby fractional, metric, numbered, or letter drill bit is usually fine only for clearance holes or rough pilot holes.