How to calibrate flow
Flow (called extrusion multiplier in PrusaSlicer and flow ratio in Orca/Bambu Studio) fine-tunes how much plastic comes out for each filament. Print a hollow cube with 1 or 2 walls, 0 top layers and no infill.
New flow = current flow × expected wall ÷ measured wall
Example: 2 walls of 0.45 mm should be 0.90 mm. If you measure 0.95 mm at 100% flow, the new flow is 100 × 0.90 ÷ 0.95 = 94.7%.
Orca Slicer and Bambu Studio also include a built-in flow test with printed patches; use either method, not both at once.
Frequently asked questions
What flow rate should I use for PLA?
Most PLA prints well at 95–100% flow (0.95–1.00 ratio) once E-steps are calibrated.
Why are my walls thicker than the line width?
Too much flow, or E-steps not calibrated. Fix E-steps first, then flow.