Clearance Hole Calculator

Find clearance and pilot hole sizes for screws.

Screw/bolt diameter

Fit type

Hole diameter 1.1

Formula: hole = bolt diameter × fit factor

Step-by-step with your numbers:

1. Values used:

2. Screw/bolt diameter = 1

3. Fit type = 1.1

5. Hole diameter = Screw/bolt diameter x Fit type = 1 x 1.1 = 1.1

Did we solve your problem today?

Find the right drill bit size for a clearance or pilot hole.

The math behind it

hole diameter = bolt/screw diameter × fit factor (close ~1.05, normal ~1.1, loose ~1.2).

1/4 in screw, normal clearance → 0.275 in.

Pilot hole?

Use a tight (close) fit for the threaded part; clearance through the top piece.