Interactive calculator
Clearance Hole Calculator
Choose a documented manufacturer recommendation or switch to a transparent planning allowance. The result always identifies which method was used.
Two different result classes
Documented recommendation returns a value published by TR Fastenings and, for selected inch sizes, independently cross-checked in a NASA technical guide. It is still not presented as an ASME or ISO tolerance.
Calculated planning allowance adds a visible fixed diametric allowance to a custom nominal size. It is useful for preliminary thinking only.
When not to use this tool
Use the drawing, design authority or licensed current standard for controlled joints. Escalate safety-critical, pressure, structural and fatigue-sensitive applications.