How to calibrate flow rate
- Calibrate E-steps first if you haven't. Flow rate fine-tunes a correctly moving extruder; it can't fix a wrong one.
- Print a single-wall cube: a 20 mm cube with 1 perimeter, 0% infill and no top layers (vase / spiralize mode works well). Note the line width in your slicer, e.g. 0.45 mm.
- Measure each wall with calipers, near the middle of the wall and away from corners and the seam. Press gently; plastic compresses.
- Enter the readings above. The calculator averages them and scales your current flow.
- Save the value per filament in your slicer's filament profile.
The formula
new flow = current flow × expected thickness ÷ measured thickness
If walls come out thicker than the line width, the printer is over-extruding and flow goes down; if thinner, it goes up.
Where to set it in your slicer
- Cura: Material → Flow (percentage).
- PrusaSlicer: Filament Settings → Extrusion multiplier (e.g. 0.96).
- OrcaSlicer / Bambu Studio: Filament → Flow ratio (e.g. 0.98). Orca also has built-in flow-rate test prints; this calculator works with any method that gives you wall measurements.
Frequently asked questions
What is the difference between E-steps and flow rate?
E-steps are a firmware setting that makes the extruder move exactly the requested filament length. Flow rate is a slicer setting, usually per filament, that compensates for differences in filament diameter and how the material behaves.
What is a normal flow rate?
Most filaments end up between about 90% and 105%. A value far outside that range usually means E-steps or filament diameter settings are wrong.
Why should I measure a single-wall print?
With one wall there is nothing for extra plastic to hide in, so wall thickness directly shows how much material was extruded.