A Simple Guide to 3D Printer Fan Speeds for PLA, PETG, ABS, and ASA
When you 3D print with FDM printers, fan speed matters a lot. The fan cools the plastic after it comes out of the nozzle. Different plastics like different amounts of cooling. The shape and size of the part also change how much fan you should use.
Too much fan can make parts weak or warp. Too little fan can make parts droopy or messy.
This guide explains fan speeds in a simple way and why they work the way they do.
What Does the Part Cooling Fan Do?
The part cooling fan blows air onto the hot plastic right after it is printed.
The fan helps:
Harden plastic faster
Improve overhangs and bridges
Make details sharper
Stop drooping
But cooling too fast can also:
Cause cracking
Cause warping
Make layers not stick together well
Shrink parts unevenly
Think of it like baking cookies.
If cookies cool too slowly, they stay soft and sag.
If they cool too fast, they can crack.
3D printing works the same way.
PLA Fan Speeds
PLA Likes Lots of Cooling
PLA is the easiest material to cool. It becomes solid quickly and does not warp very much.
Typical fan speeds:
Small detailed parts: 80–100%
Medium parts: 60–100%
Large thick parts: 30–60%
Why PLA Likes High Fan
PLA stays soft for a little while after leaving the nozzle. The fan helps freeze the shape quickly.
This helps:
Sharp corners
Tiny text
Overhangs
Bridges
Without enough cooling:
Corners become rounded
Layers can droop
Bridges sag downward
Small parts get melted by the hot nozzle revisiting the same area
Small PLA Parts Need More Fan
Small parts print quickly. The nozzle keeps coming back to the same spot while the plastic is still hot.
The fan helps cool the layer before the next layer gets printed.
Example:
Tiny figurines
Small clips
Thin towers
These often need 100% fan.
Large PLA Parts Need Less Fan
Big thick parts hold heat longer inside the plastic. Too much cooling can sometimes make layer bonding weaker.
Lowering the fan slightly helps layers stick together better.
PETG Fan Speeds
PETG Likes Medium Cooling
PETG is trickier than PLA. It stays soft and sticky longer.
Typical fan speeds:
Small detailed parts: 40–70%
Medium parts: 20–50%
Large thick parts: 0–30%
Why PETG Uses Less Fan
PETG shrinks more unevenly than PLA. Too much cooling can:
Hurt layer adhesion
Cause weak parts
Create rough surfaces
But too little fan causes:
Stringing
Blobs
Sagging overhangs
PETG needs balance.
Small PETG Parts Need More Fan
Small detailed PETG parts can become very messy without enough airflow.
Extra fan helps:
Freeze strings faster
Improve detail
Reduce blobs
Large PETG Parts Need Less Fan
Large PETG parts can crack or separate if cooled too quickly.
Lower fan helps:
Keep layers warm longer
Improve strength
Reduce stress inside the part
ABS Fan Speeds
ABS Usually Wants Very Little Fan
ABS is very sensitive to cooling. It shrinks a lot when it cools down.
Typical fan speeds:
Small detailed parts: 10–40%
Medium parts: 0–20%
Large thick parts: 0%
Why ABS Hates Strong Cooling
When ABS cools too fast:
Corners lift
Layers crack
Parts warp
Layer adhesion becomes weak
ABS likes staying warm during printing.
That is why many people print ABS inside heated enclosures.
Small ABS Parts Sometimes Need Some Fan
Tiny ABS features can stay too soft without airflow.
A little fan can help:
Sharp details
Bridges
Small overhangs
But usually only a small amount.
Large ABS Parts Usually Need No Fan
Large ABS parts build up internal stress when cooled unevenly.
Strong fan cooling can make:
Cracks between layers
Warped corners
Split parts
For large ABS parts:
Keep chamber warm
Use little or no fan
Avoid cold drafts
ASA Fan Speeds
ASA is very close to ABS but handles sunlight better.
Typical fan speeds:
Small detailed parts: 10–30%
Medium parts: 0–15%
Large thick parts: 0%
Why ASA Uses Low Fan
ASA also shrinks during cooling.
Too much fan can cause:
Warping
Cracking
Weak layers
ASA likes:
Warm chambers
Slow cooling
Stable temperatures
Small ASA Parts Can Use Some Fan
Just like ABS, a little airflow helps small features stay clean.
But too much fan quickly creates problems.
Geometry Changes Fan Needs
Thin Parts Need More Cooling
Thin walls cool very fast but can bend easily while still soft.
Extra fan helps keep shapes straight.
Examples:
Thin fins
Towers
Small clips
Figurines
Thick Parts Need Less Cooling
Large thick parts already cool slowly because they hold heat inside.
Too much fan creates uneven shrinking.
This causes:
Warping
Cracking
Weak layers
Overhangs Need More Cooling
Overhangs stick out sideways.
Without enough cooling:
Edges curl downward
Surfaces look rough
More fan helps the plastic freeze before sagging.
Quick Simple Cheat Sheet
| Material | Small Parts | Medium Parts | Large Parts |
| PLA | 80–100% | 60–100% | 30–60% |
| PETG | 40–70% | 20–50% | 0–30% |
| ABS | 10–40% | 0–20% | 0% |
| ASA | 10–30% | 0–15% | 0% |
Final Thoughts
There is no perfect fan speed for every print.
The best fan speed depends on:
Material
Part size
Geometry
Layer time
Enclosure temperature
A good rule is:
More cooling for tiny detailed parts
Less cooling for big strong parts
PLA loves cooling.
PETG likes balanced cooling.
ABS and ASA want warmth and stability.
If your prints:
Sag → increase fan
Crack → reduce fan
Warp → reduce fan
String → increase fan slightly
Have weak layers → reduce fan
Small fan changes can make a huge difference in print quality.