How closely a manufactured part's actual dimensions conform to its design intent, expressed as absolute deviation or percentage error.
Accuracy differs from precision: accuracy is closeness to true value; precision is repeatability. FDM accuracy is limited by thermal expansion, stepper resolution, belt stretch, and material shrinkage. Typical FDM: ±0.2–0.5 mm absolute, or ±0.5% for larger parts. SLA/DLP: ±0.05–0.15 mm.
Calibrate with a 20×20×20 mm test cube in XYZ. Apply shrinkage compensation in the slicer (typically 0.2–0.5% for PLA). For critical dimensions, add stock and finish to size post-print. Document calibration results per material and machine.
Accuracy varies per axis: Z-axis is layer-height dependent, XY depends on extrusion width and stepper calibration. First layer squish affects overall Z height. Part size matters: small features lose more proportionally due to rounding at extrusion width scale.
Related terms: Tolerance, Surface Roughness, GD&T (Geometric Dimensioning & Tolerancing)
| Field | engineering |
|---|---|
| Also called | print accuracy, dimensional precision |
| Source | EDi Brain: rules-core |
Engineer, author of The Big Book of 3D Printing and additive manufacturing expert