If you see a hole callout of Ø10.0 ±0.1 on a mechanical drawing, which statement is correct?

• A. The hole diameter must be exactly 10.0 mm.
• B. The hole diameter can vary with no defined range.
• C. The hole diameter must be between 9.9 mm and 10.1 mm.
• D. The tolerance applies to its depth.

Answer: (C)

Interpreting a hole size callout: the Ø symbol marks a hole, and the number 10.0 is the nominal diameter. The ±0.1 means a bilateral tolerance, so the allowable diameter ranges from 9.9 mm to 10.1 mm. Any size within that band is acceptable, and this tolerance applies to the diameter dimension itself, not to depth unless depth is specified separately. So the hole must be between 9.9 and 10.1 mm.