Retraction speed is how fast your 3D printer’s extruder pulls filament backward out of the nozzle during non-print moves. Most printers work best with a retraction speed between 25 and 50 mm/s, though the ideal value depends on your filament type and printer setup. Getting this setting right is one of the most effective ways to eliminate stringing, oozing, and blobs from your prints.
How Retraction Speed Works
When your print head finishes one section of a model and needs to travel across open space to start another, the extruder reverses direction and pulls the filament back a short distance. This reverse movement relieves pressure inside the hot end so molten plastic doesn’t drip out during the move. Without it, you get thin plastic hairs (stringing) stretched between separate parts of your print.
Retraction speed controls how quickly that pull-back happens, measured in millimeters per second. It works alongside retraction distance, which controls how far the filament is pulled back. Think of distance as how much filament retreats, and speed as how aggressively it retreats. Both settings live in your slicer software and can be adjusted independently.
Why It Matters for Print Quality
The core job of retraction speed is to relieve nozzle pressure fast enough that no plastic escapes during travel moves. When the speed is too slow, molten filament has time to ooze out before the pull-back finishes. The result is fine strings draped across your model, especially noticeable on prints with multiple separate towers or detailed features.
A properly tuned retraction speed snaps the pressure away quickly, giving the nozzle a clean break before it crosses open air. This is what produces sharp, string-free transitions between printed sections.
What Happens When It’s Too Fast
Cranking retraction speed as high as possible seems like a logical fix for stringing, but it creates its own problems. When the filament is yanked back too aggressively, the extruder motor’s drive gear can strip the filament. The gear teeth grind away the plastic surface until there’s nothing left to grip. At that point, the motor keeps spinning but the filament stops moving entirely, causing underextrusion or a complete failure to print.
You can usually spot this problem by looking at the filament after removing it from the extruder. If you see a flat, chewed-up section where the drive gear sits, the retraction speed (or distance) is too high. The fix is to reduce both values in small increments until the extrusion feels smooth again and the filament surface stays intact.
What Happens When It’s Too Slow
A retraction speed that’s too low essentially defeats the purpose of retracting at all. The filament pulls back so gradually that plastic continues to leak from the nozzle throughout the entire retraction move. You’ll see persistent stringing no matter how much you increase retraction distance, because the issue isn’t how far the filament travels but how quickly pressure is released.
Recommended Speeds by Material
Different filaments behave differently when molten, so retraction speed needs to match the material you’re printing.
- PLA: The most forgiving material. A retraction speed of 25 to 50 mm/s works well on most printers. PLA is relatively low-viscosity when melted, so it responds predictably to retraction.
- PETG: A range of 20 to 45 mm/s is effective, but PETG is noticeably more viscous than PLA. Pulling it back too quickly can actually increase stringing rather than reduce it, because the thick molten plastic stretches into threads instead of breaking cleanly. Start on the lower end and work up.
- TPU and flexible filaments: Keep retraction speed below 20 mm/s and retraction distance under 4 mm. Flexible filaments compress and buckle inside the extruder path when retracted aggressively, which can cause jams that are difficult to clear.
How to Find the Right Setting
Start at 25 mm/s and print a stringing test model, which is typically two thin towers spaced apart. If you see strings between the towers, increase the speed by 5 mm/s and print again. Keep going until the strings disappear or you start noticing signs of filament grinding (clicking sounds from the extruder motor, visible gouges in the filament, or gaps in your printed layers).
If stringing persists even at 50 mm/s, the problem likely isn’t retraction speed alone. Check your printing temperature, as a nozzle that’s too hot makes filament runnier and harder to control with retraction. Also verify that retraction distance is set appropriately: around 1 to 2 mm for direct drive extruders and 4 to 7 mm for Bowden tube setups.
Slicer Settings vs. Firmware Retraction
Most people set retraction speed directly in their slicer (Cura, PrusaSlicer, etc.), and the slicer bakes those retraction moves into the G-code file. Every retract and recover is a specific instruction with the speed and distance already defined.
There’s an alternative approach called firmware-based retraction, where the printer’s own firmware handles all retraction details. Instead of the slicer spelling out exactly how far and how fast to retract, it simply tells the printer “retract here” and “recover here” using shorthand commands. The firmware then uses its own stored speed and distance values. This lets you tweak retraction settings on the printer itself without re-slicing your model every time you want to test a new value.
Some firmware also supports automatic retraction conversion, which intercepts the slicer’s retraction commands mid-print and replaces them with the firmware’s own settings. This is useful if you’re working with older G-code files or want to override slicer values without editing the file. For most users, slicer-based retraction is simpler and works perfectly well. Firmware retraction is mainly helpful for people who frequently experiment with different materials and want to adjust retraction on the fly.
Retraction Speed vs. Prime Speed
Retraction speed has a companion setting called prime speed (sometimes called “unretract speed” or “recover speed”). This controls how fast the filament is pushed back into the nozzle after the travel move is complete. The two don’t have to match. Prime speed is often set slightly slower than retraction speed to avoid pressure spikes that cause blobs at the start of each new printed section. A common starting point is to set prime speed about 60 to 75% of your retraction speed.