Home > Fasteners 101 > Drill & Hole Size Calculator
⚙️ Drill & Hole Size Calculator
Find the correct drill bit size for tapping or clearance holes
Tap Drill Size Calculator
About Tap Drills:
The tap drill creates the hole that will be threaded. It must be smaller than the nominal thread size to leave material for the threads.
Use a 75% thread depth for most applications. This provides good strength while making tapping easier.
Clearance Hole Calculator
About Clearance Holes:
Close Fit: Minimal clearance, use when precise alignment is needed.
Normal Fit: Standard clearance for general applications.
Loose Fit: Extra clearance for easy assembly or when alignment isn't critical.
Recommended Drill Size
Quick Reference: Common Tap Drill Sizes
| Thread Size | TPI | Tap Drill | Decimal |
|---|---|---|---|
| #4-40 | 40 | #43 | 0.089" |
| #6-32 | 32 | #36 | 0.106" |
| #8-32 | 32 | #29 | 0.136" |
| #10-24 | 24 | #25 | 0.150" |
| 1/4"-20 | 20 | #7 | 0.201" |
| 5/16"-18 | 18 | F | 0.257" |
| 3/8"-16 | 16 | 5/16" | 0.3125" |
| 1/2"-13 | 13 | 27/64" | 0.422" |
Metric Tap Drill Sizes
| Thread Size | Pitch | Tap Drill |
|---|---|---|
| M3 x 0.5 | 0.5mm | 2.5mm |
| M4 x 0.7 | 0.7mm | 3.3mm |
| M5 x 0.8 | 0.8mm | 4.2mm |
| M6 x 1.0 | 1.0mm | 5.0mm |
| M8 x 1.25 | 1.25mm | 6.8mm |
| M10 x 1.5 | 1.5mm | 8.5mm |
| M12 x 1.75 | 1.75mm | 10.2mm |