Flow rate calculator
Two checks in one: tune the flow % from a test wall, and see if your speed asks for more melted plastic than your hotend can give.
Flow from a wall test
Some slicers, such as OrcaSlicer and Bambu Studio, call it the flow ratio (1.0 = 100%).
Volumetric flow
Typical PLA figures: a standard hotend melts about 10 to 15 mm³/s (12 used here), a high-flow one about 20 to 35 (25 used here). PETG, ABS and TPU melt slower. Your hotend's own figure, or a max flow test, beats these.
Worked example
Flow 100%, the wall should be 0.45 mm and measured 0.48 mm: 100 x 0.45 / 0.48 = 93.75%. Speed: 0.2 mm layers x 0.45 mm lines x 100 mm/s = 9 mm³/s, which a standard hotend (about 12) can melt. At those settings it tops out near 12 / 0.09 = 133 mm/s.
How it works
- New flow = current flow x wall should be / wall measured.
- Volumetric flow = layer height x line width x speed, in mm³/s.
- Top speed = hotend's melt rate / (layer height x line width).
Everything runs in your browser. Nothing is sent anywhere and there is no account.
Questions
What test print do I use?
A 20 to 30 mm hollow cube with one wall, no top and no infill (vase or spiral mode works). Measure each side in the middle, away from the corners, and average them.
What happens if I go over the hotend's flow?
The hotend cannot melt the plastic fast enough: walls come out thin and weak, layers split, and the extruder may click. Slow down, print a little hotter within the filament's range, or fit a high-flow hotend.
Should I set E-steps first?
Yes, on printers where you can. E-steps sets the extruder for every filament; flow then fine-tunes each one. See the E-steps calculator.