3DPrintCalcs
Hinge Calculator — Print-in-Place Hinge Dimensions
Design print-in-place hinges with correct clearance and pin dimensions.
How We Calculate This
Hinge Dimension Formulas
- Hole diameter = Pin diameter + 2 x Clearance
- Min wall = Nozzle diameter x Wall multiplier (default 3)
- Outer diameter = Hole diameter + 2 x Min wall
- Gaps between knuckles = Knuckle count − 1
- Knuckle length = (Hinge width − Gaps x Clearance) / Knuckle count
- Knuckle pitch = Knuckle length + Clearance (centre-to-centre slot spacing along the pin)
The clearance gap around the pin allows rotation. The knuckles alternate between the two hinge halves. At least 3 knuckles are needed (2+1) for the hinge to function properly.
This calculator assumes a flat-printed hinge, so the same clearance value sets both the radial gap around the pin and the axial gap between adjacent knuckles — both lie in the XY plane where 0.2-0.3 mm is the sweet spot for a 0.4 mm nozzle. If you print the barrel standing up (knuckles stacked in Z), set the axial gap to at least two layer heights instead, as Z-direction fusing behaves differently.
Frequently Asked Questions
Typically 0.25-0.4mm clearance around the pin, depending on your printer. Too tight and the hinge will not move; too loose and it will be wobbly. Start with 0.3mm and adjust based on test prints.
Three knuckles (2 on one side, 1 on the other) is the minimum for a working hinge. Five knuckles gives a stronger, smoother hinge. More knuckles = stronger but harder to print cleanly.
Yes, most print-in-place hinges need to be gently flexed to break the slight bonds between the pin and knuckle. Work them back and forth carefully. If they are stuck solid, the clearance was too small.
For FDM printing, pins of 3-6mm diameter work well. Below 3mm, the pin becomes fragile. Above 6mm, the clearance gaps become large relative to print features. The pin should be at least 6x the nozzle diameter.
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Last updated: February 2026
All calculations are estimates. Always verify settings with test prints before committing to final prints.