Expected deviation between the nominal CAD dimension and the measured printed dimension, per technology.
Dimensional tolerance is the band of acceptable deviation from the target dimension. In AM it arises from thermal effects (shrinkage/warping in FDM, DMLS), powder bed consolidation (SLS), or resin photopolymerisation spread (SLA). Tolerance is anisotropic: XY is typically tighter than Z.
Always design mating features using the worst-case tolerance of the chosen technology. For functional fits (press-fit pins, shaft holes) subtract the expected error from the nominal size and verify with a printed coupon. Post-machining DMLS or SLS parts brings tolerance to ±0.02 mm.
Tolerance figures assume a calibrated machine and stable material. Uncalibrated FDM printers can reach ±0.5 mm or worse. Resin shrinkage post-cure can shift SLA parts by 0.3–0.5% overall scale.
Related terms: Clearance for moving / mating parts, Press-fit joint, Interference vs clearance fit selection
| Theme | assembly |
|---|---|
| FDM | ±0.2 mm typical; depends on calibration and material shrinkage. |
| SLA | ±0.05–0.1 mm; high-resolution resin allows tight tolerances. |
| SLS | ±0.3 mm typical; powder bed sintering introduces thermal spread. |
| DMLS | ±0.1–0.2 mm plus post-machining for tight tolerances. |
| Also called | print accuracy, dimensional accuracy |
| Source | sources/2026-04/2026-04-24--3d-printing-best-practices-guide, sources/2026-04/2026-04-30--fdm-starterpack-bg |
Engineer, author of The Big Book of 3D Printing and additive manufacturing expert