Bolt Hole Calculator — Clearance & Tap Hole Sizes
Calculate clearance and tap hole sizes for standard metric bolts.
How We Calculate This
Bolt Hole Formulas
- Clearance hole = Bolt diameter + 0.5mm + Printer tolerance
- Close fit hole = Bolt diameter + 0.2mm + Printer tolerance
- Tap drill hole = Standard tap drill + Printer tolerance
- Counterbore = Head diameter + 0.5mm + Printer tolerance
Printer tolerance is added to all holes because FDM holes print smaller than designed. The clearance allows the bolt to pass freely, while tap drill holes are sized for thread cutting with a tap.
Frequently Asked Questions
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Last updated: February 2026
All calculations are estimates. Always verify settings with test prints before committing to final prints.