A fast printer is not fast if the hotend cannot melt plastic quickly enough. Volumetric flow is that real limit, in cubic millimetres per second. This works it out both ways: the flow your settings demand, and the top speed your hotend allows.
How to use it
- Enter layer height, line width and print speed to see the volumetric flow your settings demand.
- Or enter your hotend's flow limit, layer height and line width to get the maximum speed you can run.
- Compare the demand to your hotend's limit: staying under it means the melt keeps up.
- If demand is over the limit, lower speed, layer height or line width until it fits.
What it does
Both directions
Demand from settings, or max speed from a limit. Whichever number you are missing, this gives it.
The real bottleneck
Cranking speed past the hotend's melt rate just under-extrudes. This shows you where that wall is.
Simple inputs
Three numbers you already know from your slicer, and the answer that governs how fast you can actually print.
What people use it for
Speed tuning
You want faster prints. Find whether your hotend or your motors are the limit before you chase the wrong one.
Buying a hotend
Deciding on a high-flow upgrade? See exactly what flow you would need to hit your target speed.
Large nozzles
A 0.6 or 0.8mm nozzle at thick layers demands a lot of flow. Check your hotend can feed it.
Good to know
- Line width is usually 100 to 120 percent of nozzle diameter. Use your actual slicer value, not the nozzle size, for an accurate figure.
- Run a flow-limit test in Orca or by hand to find your hotend's true maximum for a given filament before trusting a catalogue number.
- PETG and other materials melt differently: a hotend's PLA limit is not its PETG limit. Test per material.
- The slowest wall speed, not the fastest infill speed, often sets surface quality. Volumetric flow governs both.
Questions
What is volumetric flow?
The volume of plastic your hotend melts and pushes per second, in cubic millimetres per second. It is the real speed limit of a printer, because a hotend can only melt so fast no matter how quickly the motors move.
How do I calculate it?
Volumetric flow equals layer height times line width times print speed. At 0.2mm layers, 0.4mm lines and 150mm per second, that is 12 cubic millimetres per second, which is a lot to ask of many hotends.
What is my hotend's limit?
A stock hotend often maxes around 8 to 12 cubic millimetres per second for PLA, a high-flow hotend 20 to 30 or more. Below the limit you are motor-limited, above it the hotend cannot keep up and you under-extrude.
How do I find the maximum speed?
Enter your hotend's flow limit and a layer height and line width, and the tool gives the top print speed you can run before the melt cannot keep pace.
Also called
Known as a volumetric flow calculator, max flow rate calculator, mm3/s calculator, or maximum print speed calculator. It finds the melt-rate ceiling on how fast you can print.