Supports and Overhangs in 3D Printing
An overhang is a printed feature with nothing solid underneath it, and a bridge is an unsupported span between two points, and both can sag or print rough once the angle or gap outruns what the material and cooling can hold up during printing.
What is the maximum overhang angle for FDM 3D printing?
45 degrees is a slicer default, not a physical constant. Published slicer and vendor thresholds sit around 40 to 50 degrees, and the real limit for your part depends on cooling, material and machine.
Every figure below is one source's own default or guideline, not a shared industry standard. A steeper angle can still print clean with enough cooling, and a shallower one can still sag with too little.
| Source | Overhang limit (degrees, as published) | Provenance |
|---|---|---|
| Cura (Ultimaker) | 50, measured from vertical | Cura shared printer definition file |
| PrusaSlicer | Automatic detection, no fixed angle by default | PrusaSlicer print configuration source |
| Markforged | 40, measured to horizontal | Markforged Composites Design Guide v1.4 |
| Protolabs Network | Usually up to 45 | Protolabs Network FDM design guidelines page |
How far can FDM print a bridge without sagging?
Protolabs Network says bridging marks are always present unless the bridge is under 5 mm, and that once a bridge passes 5 mm, sagging or support marks can occur. No manufacturer publishes a maximum bridge span in millimeters as a specification.
A peer-reviewed study on PLA bridging found that ISO/ASTM 52910 sets no explicit maximum bridge span, and that a 10 mm practical limit some shops use is empirical, not written into any standard.
What this page does not tell you
- This page compares slicer defaults and manufacturer guidance, not one shared industry rule. Your own geometry, material and cooling still decide what prints clean without support.
- No manufacturer publishes a bridging span in millimeters as a specification. Any figure describing a safe bridge length is a practical guideline or a study finding, not a datasheet number.
- These figures come from each source's own printers, slicers and test setups. None of it was measured on the machines that will make your part.
When to print a test coupon instead
Print a small overhang and bridge test coupon at the angles and spans you are considering before committing to a full run, especially when the bridge has to look clean or carry load while it sets. Send the file through a review request and tell us which angles and spans to check. A person reviews your request and follows up by email.
Sources
- fdmprinter.def.json (support angle default), Ultimaker (Cura)
Cura's shared printer definition file. The support overhang angle default value is 50 degrees, measured from vertical.
- PrintConfig.cpp (support angle default), PrusaSlicer (Prusa Research)
PrusaSlicer's print configuration source. The support material threshold angle default is 0, meaning automatic detection rather than a fixed degree value.
- Composites Design Guide v1.4, Markforged
States a minimum part dimension of 1.6 mm in X, 1.6 mm in Y and 0.8 mm in Z, on Onyx material with 100 micron layers.
- Modeling with 3D Printing in Mind, Prusa Knowledge Base
Gives perimeter arithmetic on a 0.4 mm nozzle: 1 perimeter 0.45 mm, 2 perimeters 0.9 mm, 3 perimeters 1.35 mm, 4 perimeters 1.8 mm. States a wall thinner than one nozzle perimeter is not printable.
- FDM 3D printing design guidelines, Protolabs Network
States a minimum wall thickness of 0.8 mm at both the prototyping and production tiers, and a minimum feature size of 2.0 mm.
- Peer-reviewed PLA bridging study, PMC (peer-reviewed)
States ISO/ASTM 52910 sets no explicit maximum bridge span, and that a 10 mm practical bridging limit used in the field is empirical, not written into any standard.
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Published 5 September 2026.