3D Print Tolerance & Clearance Calculator
Find the right hole or pin diameter for every kind of fit on FDM and resin printers, plus a heat-set insert hole size chart.
Moves smoothly (drawers, sliders, hinges).
Design with these values
How to use it
- 1Choose your printer type and the fit you need.
- 2Choose what you are designing — a hole for a known pin, or a pin for a known hole — and enter the diameter.
- 3Use the result in your CAD model.
- 4Print a small test piece first, then set “Adjust for your printer” based on how it fits.
Clearance chart (diameter)
| Fit | FDM | Resin |
|---|---|---|
| Press fit | 0.10 mm | 0.05 mm |
| Snug fit | 0.20 mm | 0.10 mm |
| Sliding fit | 0.30 mm | 0.15 mm |
| Loose fit | 0.40 mm | 0.20 mm |
| Print-in-place | 0.50 mm | 0.30 mm |
Heat-set insert hole sizes
| Thread | Hole | Min. wall |
|---|---|---|
| M2 | 3.2 mm | 1.5 mm |
| M2.5 | 4.0 mm | 1.6 mm |
| M3 | 4.0 mm | 1.6 mm |
| M4 | 5.6 mm | 2.0 mm |
| M5 | 6.4 mm | 2.5 mm |
| M6 | 8.0 mm | 3.0 mm |
For standard-length brass inserts. Always confirm with the insert maker’s datasheet.
3D print tolerances for press, sliding and loose fits
Tolerance is the gap you design between parts that fit together. Too little and they will not assemble; too much and they rattle. On a tuned FDM printer, start with a total (diameter) clearance of about 0.1 mm for a press fit, 0.2 mm for a snug fit, 0.3 mm for a sliding fit and 0.4 mm for a loose fit; resin printers need roughly half.
These are starting points. Print a small tolerance test, measure what works on your machine and material, and put the difference into the adjustment field.
Frequently asked questions
What clearance should I use for print-in-place parts?
A good FDM starting point is 0.4–0.5 mm on the diameter (0.2–0.25 mm per side). Well-tuned printers such as Bambu Lab machines can often go lower.
Why do holes print smaller than designed?
Extruded plastic squishes outward slightly and small holes are affected most. That is why you add clearance, and some slicers have an X-Y hole compensation setting.
What hole size do I need for an M3 heat-set insert?
About 4.0 mm for standard brass M3 inserts, with at least 1.6 mm of wall around it. Check your insert maker’s chart, as sizes vary slightly.
What tolerance should I use for print-in-place hinges?
Start around 0.4–0.5 mm on FDM (0.2–0.25 mm per side) and reduce it if the hinge prints loose.
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