Line width
How wide each line of plastic comes out when a line type has no width of its own. Wider gives stronger, faster walls; thinner gives more detail.
How it works
The nozzle lets out a thread of melted plastic and presses it against the previous layer. The width of that line doesn't depend only on the nozzle hole, but on how much plastic the printer pushes for every millimeter it moves: more plastic, wider line; less, thinner.
With a 0.4 mm nozzle, the usual value is 0.42 mm, just a bit wider than the hole so neighboring lines overlap well. This value is the “fallback”: it's used for any line type whose own width is set to 0. If you type a percentage, it's calculated from the nozzle diameter (100% = 0.4 mm).
There's a physical limit: the flat tip of the nozzle is what presses the plastic down, so it's best not to go above 1.5 times the diameter. Below 0.75 times, the thread stretches and sticks poorly.
When to change it
- Almost never: the factory profiles already come with a tuned value. It's better to change the specific widths (outer wall, infill).
- A shelf bracket or a hook that will carry weight, with no fine detail: raise it to 0.5 or 0.6 mm with a 0.4 nozzle. Walls come out more solid and with fewer passes.
- A keychain with small text: lower it to 0.35 or 0.38 mm, but only in “Outer wall”, not here.
Typical values
| Value | What for |
|---|---|
| 0.30 | Sensible minimum with a 0.4 nozzle (0.75×) |
| 0.42 | Default in Bambu profilesdefault |
| 0.50 | More strength, a bit less definition |
| 0.60 | Sensible maximum (1.5×) |
Watch out for
- On bridges (stretches that cross open air) and overhangs (parts that stick out with nothing underneath), this value doesn't apply: the plastic falls into the air, ends up round, and its width can't be controlled there.
- A wider line at the same speed needs more plastic per second. If you ask for more than the nozzle can melt (about 21 mm³/s with a regular PLA), less plastic comes out than needed and you get gaps.
- Changing the width changes how many walls fit in a given thickness and how the infill overlaps them; check the result in the preview.
Goes well with
What Bambu Studio saysits help card, quoted
What Bambu Studio says
Default line width if some line width is set to be zero
Bambu Studio tooltip for this setting · AGPL-3.0
Read more at the official source
In your profile0.20mm Standard @BBL A1 · 0.42 mm
In Bambu Studio, the profile 0.20mm Standard @BBL A1 sets it to0.42 mm
In other slicers
- Orca Slicer
- DefaultQuality › Line width
- PrusaSlicer
- Default extrusion widthAdvanced › Extrusion widthIf entered as a %, Prusa computes it from the layer height, not the nozzle.
- Cura
- Line WidthQuality
Names taken from each program's code (Orca Slicer 2.4.2, PrusaSlicer 2.9.6, Cura 5.13.0). Credits