🎚️ Flow Rate Calculator
Enter your current flow %, the target wall thickness and the wall you measured to get the corrected flow rate.
New flow / extrusion multiplier
95.2%
Your wall printed thicker than target, so flow comes down. Enter this as the flow rate (Cura) or extrusion multiplier (PrusaSlicer/OrcaSlicer; ÷100 → 0.952).
How to measure:
- Print a single-wall calibration cube (0 top/bottom layers, 0% infill, 1 perimeter) at your line width.
- Measure the wall with calipers at several spots and average, that's the "measured wall".
- The "target wall" is your slicer's line width (often the nozzle size, e.g. 0.40 mm).
New flow = current × (target ÷ measured). This is the classic single-wall method; the measurement is a little noisy, so average several readings and re-check after big changes. Calibrate E-steps first, then flow. 🔒 In your browser.
How the flow rate calculator works
Flow rate (or extrusion multiplier) fine-tunes how much plastic goes into each line. You print a single-wall test at a known line width, measure the actual wall with calipers, and correct: new flow % = current % × (target wall ÷ measured wall). If your wall came out too thick, flow comes down; too thin, it goes up. The tool gives the new percentage and the decimal extrusion multiplier for PrusaSlicer/OrcaSlicer.
This is the classic single-wall method and the measurement is a little noisy, so measure the wall in several places and average. Calibrate your E-steps first, flow assumes the extruder is already moving the right amount of filament. Some printers now prefer dedicated flow-test patterns, but the single-wall method is quick and widely used.
Frequently asked questions
How do I calibrate flow rate?
Print a single-wall cube (one perimeter, no top/bottom or infill), measure the wall with calipers, and set new flow = current × (target ÷ measured), where the target is your line width. Average several measurements for reliability.
What is the extrusion multiplier?
The same thing as flow rate, expressed as a decimal (a flow of 95% is an extrusion multiplier of 0.95). Cura calls it "flow"; PrusaSlicer and OrcaSlicer call it "extrusion multiplier". It scales how much filament each move deposits.
Should I calibrate E-steps or flow first?
E-steps first. E-steps is a hardware calibration that makes the extruder move the correct length of filament; flow is a finer software adjustment on top. Getting E-steps right means flow only needs a small tweak.
My walls are too thick, what flow do I use?
Lower it. If a 0.40 mm target wall measured 0.42 mm, new flow = current × 0.40 ÷ 0.42 ≈ 95% of the current value. Enter your numbers for the exact figure.
Why measure a single-wall print?
A single perimeter with no infill or top layers isolates the extrusion width, so the wall thickness directly reflects how much plastic is coming out, making it a clean target for calibrating flow.