3/8 inch Drill Bit Size
A 3/8 inch drill bit is 0.3750 inches or 9.53 mm. It is smaller than 10 mm, so use 25/64 inch or 10 mm when an exact 10 mm hole matters.
Quick Answer
Decimal
0.3750 in
Metric
9.53 mm
Closest
10 mm
3/8 inch Drill Bit Equivalent Chart
| Size | Decimal Inches | Metric | Note |
|---|---|---|---|
| 3/8 inch | 0.3750 in | 9.53 mm | Exact size |
| 10 mm | 0.3937 in | 10.00 mm | Common metric oversize |
| V | 0.3770 in | 9.58 mm | Nearby letter drill size |
| 23/64 inch | 0.3594 in | 9.13 mm | Smaller fractional option |
Common Uses
Lag bolt pilot holes, larger through-holes, and general construction drilling.
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.
3/8 inch Drill Bit FAQ
What are the inch and metric dimensions for 3/8 inch?
3/8 inch drill bit measures 0.3750 in and 9.53 mm.
What is the closest common equivalent to 3/8 inch?
10 mm is the closest common equivalent listed here. It measures 0.3937 in or 10.00 mm.
Can I substitute another bit for 3/8 inch?
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.