Cooling is where PETG splits the difference between PLA (which loves maximum fan) and ABS (which wants almost none). Get it wrong and you either get weak, delaminating layers or ugly, drooping overhangs. Here is the balance.
Why PETG hates too much cooling
Layer bonding depends on each new layer partially re-melting the one below it. A strong part-cooling fan freezes each layer too fast, so the layers never properly weld — the print looks fine but snaps along layer lines under load. PLA tolerates (and likes) full cooling; PETG does not.
Too much fan also makes PETG more brittle and can worsen warping on the rare occasions PETG warps at all.
Recommended PETG fan settings
A good starting point:
- First 2–3 layers: fan off, for maximum bed adhesion.
- Body: 30–50% part cooling.
- Bridges and steep overhangs: temporarily higher, if your slicer supports overhang/bridge fan overrides.
If your parts look great but feel weak, lower the fan first. If overhangs droop and detail blurs, nudge it up. The goal is the minimum cooling that gives acceptable overhangs — strength comes first with PETG.
FAQ
What fan speed for PETG?
Why are my PETG layers weak?
Do I need any fan at all for PETG?
More PETG guides
Reviewed 2026-08-18. Starting points and general guidance — always calibrate for your filament brand and machine.