3D Printing Calculators
Maximum Volumetric Flow Rate Calculator
https://www.3dsizing.com/calculators/volumetric-flow/
Estimate only — not firmware, a slicer profile or a shop quote. Confirm on a test print.
Maximum Volumetric Flow Rate Calculator
Hotends melt plastic at a limited cubic millimetres per second. This tool shows the flow your current profile asks for and the speed ceiling if you already know the hotend’s max flow.
Inputs
Results
- Volumetric flow
- 5.04mm³/s
- Max speed at this layer
- 142.9mm/s
- Over hotend max?
- No
Q_max divided by height × width.
Yes means this speed asks for more melt than the limit you entered.
Calculation method
Volumetric flow Q = layer height × line width × print speed. All three are millimetres and millimetres per second, so Q is mm³/s. Maximum speed at that layer is the hotend’s max flow divided by (height × width). The over-max flag is 1 when Q exceeds the entered limit. Imperial converts mm to inches and mm/s to in/s and mm³/s to in³/s; the physics is unchanged.
Exact formula
Q = h × w × v with h and w in millimetres and v in mm/s, so Q is mm³/s. v_max = Q_max / (h × w). Over-max is true when Q > Q_max. Limits: Q uses a rectangle h×w, not the true stadium extrusion. Max flow is the number you typed, not a measured melt test.
Temperature is part of max flow
Hotter plastic flows easier until it degrades. A number from 250 °C PETG does not apply to 200 °C PLA.
Acceleration still matters
Short segments never reach the speed you typed. Volumetric flow on tiny infill is lower than the profile’s headline mm/s.
Frequently asked questions
What max flow should I type?
Measure it: increase speed on a single-wall cube until extrusion starves, then compute Q at that speed. Vendor charts are a starting guess.
Does 0.6 mm nozzle change the formula?
The formula is the same. Line width and max flow both go up, so v_max may or may not rise.
Why not 100% of nozzle as line width?
Many profiles use ~105–120% for bonding. Wider lines raise Q at the same speed.
Is this the same as slicer flow %?
No. Slicer flow scales extrusion multiplier. This Q is geometric: height × width × speed.
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