Materials & tolerances: clearance for 3D printed parts

Recommended clearance ranges by material and by fit type. Use these as a starting point when designing parts that need to snap, slide, thread, or hinge together — then tune from a small test print.

Baseline tolerance by material

"General" is the dimensional tolerance you can reasonably expect on a nominal feature under 100 mm. Larger parts drift more — mostly from thermal shrinkage — so add margin proportionally on long dimensions.

Material	General	Press fit	Sliding fit	Threads (per side)	Hinges
PLA	±0.15 mm	0.10–0.15 mm	0.20–0.30 mm	0.20 mm	0.30 mm
PETG	±0.20 mm	0.15–0.20 mm	0.25–0.35 mm	0.25 mm	0.35 mm
ABS	±0.25 mm	0.20–0.25 mm	0.30–0.40 mm	0.30 mm	0.40 mm
TPU	±0.30 mm	not recommended	0.40–0.60 mm	avoid printed threads	0.30 mm (living hinge)

Values are per-side clearance between mating surfaces. Double them when specifying diameter-on-diameter (hole vs. shaft).

Notes by material

PLA: Rigid, dimensionally stable. Fine detail holds well.
PETG: Slight elephant's foot — expect a touch of squish on the bottom layer.
ABS: Shrinks ~0.7% while cooling — add clearance on long dimensions.
TPU: Flexible — mating parts deform under load; oversize openings.

Clearance recipes for common fits

Press fit (interference)

Aim for 0.10–0.20 mm per side on rigid materials. Chamfer the leading edge 0.5 mm × 45° so the parts self-align, and orient the mating hole vertically to avoid the elephant's-foot bulge on the bottom layer. Skip press fits in TPU — it deforms under load.

Sliding / clearance fit

Use 0.20–0.40 mm per side. Sanded PLA slides smoother than as-printed PETG; if a shaft has to rotate, err toward the loose end of the range and add a dry lubricant.

Printed threads

For threads printed in place, add 0.20–0.30 mm per flank and use a coarse pitch (M6 or larger). For anything under M6, or for repeated assembly, drop in a heat-set brass insert instead — the hole should match the insert's shank OD.

Hinges & snap fits

Living hinges work best in PETG or TPU with a wall around 0.4–0.6 mm at the flex point. For pin hinges, leave 0.30–0.40 mm around the pin and orient the pin axis along the print direction so layer lines don't run through the pivot.

Holes & bores

Printed holes come out 0.10–0.20 mm undersized because of extrusion overlap. Either oversize the model by that amount, or drill/ream after printing for a precise diameter.

How to dial it in

These numbers assume a 0.4 mm nozzle at 0.2 mm layers on a well-calibrated printer. If a first assembly is too tight, adjust in 0.05 mm steps — that's the smallest change most FDM printers reliably resolve. Print a small tolerance test alongside the real part so you're not reprinting the whole assembly to check one gap.

Materials & tolerances

Pick clearance for millimetre-sized parts