Select the screw
Choose the unit system, screw size, and fit class.
Interactive dimensional reference
A clearance hole lets a screw or bolt shank pass through freely — unlike a tap drill, which cuts internal threads. Select a screw size and fit class below to get the recommended clearance drill instantly, or scan the full inch and metric reference tables.
Choose the unit system, screw size, and fit class.
Values update instantly from your selections.
Shop jobber-length twist drills sized to the exact clearance diameter you just looked up.
Also fitting a counterbore for a socket-head cap screw? See the companion Counterbored Holes Dimensions (imperial) reference for counterbore and countersink sizes.
Complete reference
Number sizes #0–#12 and fractional 1/4"–1", Close Fit and Free Fit.
| Screw size | Screw diameter | Close fit drill | Close fit dia. | Free fit drill | Free fit dia. |
|---|
Complete reference
M2–M20, Close, Medium, and Free fit (mm).
| Screw size | Close fit | Medium fit | Free fit |
|---|
Reference: general machinery's-handbook-style clearance hole data for machine screws and bolts (Close Fit / Free Fit, inch; Close / Medium / Free fit, metric per ISO 273 / ASME B18.2.8 pattern), cross-checked against published clearance hole drill charts (engineersbible.com, University of Virginia Physics Dept. reference PDF, EngLab clearance hole tables).