About this tool
Volumetric Flow Rate & Max Speed Calculator is a free, in-browser tool that connects the three numbers that govern how fast a hotend can print: layer height, line width and print speed. It has two modes — compute the volumetric flow your settings demand, or find the maximum print speed a hotend's flow limit will allow. Nothing is uploaded.
The extruded cross-section per pass is layer height × line width, so the volumetric flow is that area × print speed, in mm³/s. At 0.2 mm layer, 0.4 mm width and 60 mm/s that is 0.08 × 60 = 4.8 mm³/s. Switch to max-speed mode and the relationship inverts: max speed = max flow ÷ (layer height × line width), so a hotend rated for 15 mm³/s can run about 187 mm/s at those settings.
Use it to check whether a target speed will out-run your hotend — every hotend has a maximum sustainable flow (a stock unit is often ~8–12 mm³/s, a high-flow one 20–30+). If the flow your speed demands exceeds that ceiling, you get under-extrusion; this tool tells you the safe speed before you slice.
Frequently asked questions
How is volumetric flow rate calculated?
Flow = layer height × line width × print speed. Layer height times line width is the cross-section of one extruded line (mm²); multiplying by speed (mm/s) gives the volume of plastic melted per second in mm³/s.
How do I find my max print speed?
Switch to max-speed mode and enter your hotend's maximum volumetric flow. The tool computes max speed = max flow ÷ (layer height × line width). Printing faster than that starves the nozzle and causes under-extrusion.
What is a typical hotend flow limit?
A stock hotend often sustains around 8–12 mm³/s; high-flow hotends (Volcano, Revo, CHT nozzles) reach 20–30 mm³/s or more. The real limit depends on nozzle, heater and material — run a flow test to find yours, then enter it here.
Does a bigger nozzle or thicker layer lower the max speed?
Yes. A larger line width or layer height increases the area per pass, so for a fixed flow limit the maximum speed drops proportionally. That is why fine 0.1 mm layers can run fast while thick 0.3 mm layers hit the flow ceiling sooner. All math runs in your browser.
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