3D printing fit calculator
Tube outer diameter 30 mm, and you need a matching cap? Or an opening of 30 mm, and you need the matching plug? Enter your counterpart dimension and the desired clearance — the calculator instantly shows you the model dimension.
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Clearance per side or total?
This is the most common source of confusion with fits. If an opening should be 0.40 mm larger than a plug, that can mean two different things: 0.40 mm total difference, or 0.40 mm per side — meaning 0.80 mm total difference. Example: a tube with a 30.00 mm outer diameter and 0.20 mm clearance per side gives an opening of 30.00 + 2 × 0.20 = 30.40 mm. That's why you can choose between both definitions above.
Why the calculator can't guarantee a perfect fit
The calculated model dimension is a geometric starting value. Printer, material, calibration, orientation and geometry all affect how the real printed part actually turns out.
Measure first, then add clearance
A clean result starts with a cleanly measured counterpart dimension. Measure the real part, not just an assumed nominal value.
A small test saves filament
For critical fits, print a small test piece with the calculated clearance first, rather than printing the whole part directly. That saves time and material if the fit needs adjusting.
Create an end cap with this dimension