An overhang is any surface that angles outward past the vertical, with no support under it. Up to about 45 degrees most printers handle it clean. Past that, the filament has nothing to land on, so it sags, curls, or drools into a mess. Per Prusa’s overhang guidance, the fix is more cooling, a gentler angle, or a support.
The sag is cosmetic on a rough part, but it ruins a fitting surface or a thread. Work the causes in order and reprint the same test after each change.
Your material sets the limit. PLA holds overhangs the best, because it takes high cooling and stiffens fast. PETG and ABS sag more.
What drives it
| Likely cause | Fix | Severity |
|---|---|---|
| Part cooling too low | Raise part cooling toward 100 percent for the overhang layers. | hi |
| Overhang angle too steep | Add a support under it, or orient the part so the angle stays under 45 degrees. | hi |
| Print speed too high | Slow the outer walls to 25 to 30 mm/s on the overhang. | md |
| Nozzle too hot | Lower the nozzle about 5 C so the filament sets faster. | md |
| Layer height too tall | Lower the layer height so each overhang step is smaller. | lo |
Fast fixes to try first
Print an overhang test tower and watch where it starts to sag, then work top to bottom and reprint after each step.
Raise the cooling
Set part cooling to 80 to 100 percent for the overhang layers and reprint.
Slow the outer walls
Drop the outer wall speed to 25 to 30 mm/s and reprint.
Lower the nozzle temp
Cut the nozzle about 5 C so the filament stiffens sooner.
Add a support
If the angle is steep, turn on supports for the overhang and reprint.
If the quick fixes stall
When cooling and speed do not hold the overhang up, the model setup is the next place to look.
Orient the part
Rotate the model so the overhang faces up or sits against a wall, under 45 degrees.
Lower the layer height
Drop the layer height so each overhang step is smaller and easier to hold.
Tune the fan ducts
Make sure the part-cooling fan hits the nozzle from both sides, since a one-sided blast sags one edge.
What your material changes
PLA handles overhangs the best, because it takes high cooling and stiffens the moment it leaves the nozzle. PETG and ABS stay soft longer, so they sag more and want slower speeds and full cooling. TPU sags badly on steep overhangs and is best kept under 45 degrees.
Habits that backfire
A few common choices trade the sag for a new problem.
Avoiddo not
- Dropping the temp so far the layers go weak.
- Running the overhang at full speed and hoping cooling saves it.
- Leaving a steep overhang unsupported to avoid the cleanup.
- Changing cooling, speed, and temp in one pass, so the real cause stays hidden.
Key takeaways
- Overhangs sag past about 45 degrees when cooling and the angle are wrong.
- Raise part cooling, slow the outer walls, and lower the temp first.
- Add a support or orient the part for steep angles.
- PLA holds overhangs best; PETG and ABS sag more.
For the flat-span version, the bridging guide covers filament stretched across an open gap, and the filament storage guide covers keeping spools dry.
Related guides
Related
More in this area
Cross-reference
Sources & methodology
2 citations · reviewed 2026-07-10- 01Prusa Knowledge Base: Poor bridging and overhang sagaccessed 2026-07-09Tier 1
- 02All3DP: How to master overhangs past 45 degreesaccessed 2026-07-09Tier 2