Flow rate, also called the extrusion multiplier, scales how much plastic the printer lays down. Set it from a measured wall and your dimensions come right, your top surfaces close cleanly, and gaps disappear. This gives you the exact percentage.
How to use it
- Print a single-wall test at a known line width with your current flow setting.
- Measure the wall thickness with calipers in several spots and average it.
- Enter the current flow percentage, the wall width you set, and the width you measured.
- The tool gives the corrected flow. Set it in your slicer's filament settings.
What it does
Measured, not guessed
Flow is the one setting best set from a caliper reading. This turns that reading into the exact percentage.
Per filament
Different brands and colours flow differently. Do this once per filament and save it against that filament profile.
Fixes real symptoms
Gaps between top infill and walls, dimensions running large, rough tops: all flow, and all fixed by the right percentage.
What people use it for
A new filament
New spool, new brand. A two-minute single-wall test and this gives you the flow to save with it.
Dimensional parts
Enclosures, gears, anything that has to fit. Correct flow is the difference between a part that assembles and one that binds.
Clean top surfaces
If tops look under-filled or over-stuffed, flow is usually the cause. Dial it here.
Good to know
- Measure the wall in several places and average: a single reading can catch a blob or a thin spot.
- Use a slow, single perimeter for the test so there is nothing but the wall to measure.
- Keep flow within roughly 90 to 110 percent. A correction far outside that points back at E-steps or a partial clog.
- Save the result to the filament profile, not the printer, since it is a property of the filament.
Questions
How do I measure flow rate?
Print a single-wall calibration cube with a known wall line width, then measure the wall with calipers in a few places and average it. Enter your current flow percentage, the wall width you set, and the width you measured.
What is the formula?
New flow equals current flow times the target wall width divided by the measured wall width. If you set 0.4mm walls and measured 0.42mm, you were over-extruding and flow comes down.
Is flow the same as extrusion multiplier?
Yes. Different slicers call it flow, flow rate, or extrusion multiplier, and it is the same knob: a percentage scaling of how much plastic is pushed. 100 percent means no change.
Flow or E-steps first?
E-steps first, because it makes the extruder accurate at the hardware level. Then flow, per filament, to fine-tune the amount that lands on the wall. Doing flow before E-steps bakes a hardware error into a per-filament setting.
Also called
Searched as a flow rate calculator, extrusion multiplier calculator, flow calibration tool, or flow percentage calculator. It corrects how much plastic lands on the part.