Calculate the volume of plastic extruded per second to prevent hotend clogging.
Millimeters (mm)
Millimeters (mm)
Millimeters per second (mm/s)
Usually 1.75mm or 2.85mm
Volumetric Flow Rate:0.00 mm³/s
Equivalent Filament Feed Speed:0.00 mm/s
Understanding Volumetric Flow Rate in 3D Printing
Volumetric Flow Rate is one of the most critical physics constraints in Fused Deposition Modeling (FDM) 3D printing. It represents the volume of thermoplastic material that your hotend melts and pushes out through the nozzle per second. Calculating this value helps you avoid underextrusion, clicking extruders, and failed prints caused by exceeding your hotend's melting capacity.
The Formula
The calculation is relatively simple and relies on the geometry of the line being printed:
Layer Height (mm): The thickness of each slice of the print.
Extrusion Width (mm): The width of the plastic line laid down (usually 100-120% of nozzle diameter).
Print Speed (mm/s): The velocity at which the print head moves.
Why This Calculation Matters
Every hotend has a "Maximum Volumetric Flow Rate" (Max MVS). This is the physical limit of how fast the heater block can transfer thermal energy into the filament to melt it. If your slicer settings request a flow rate higher than your hotend's capability, the plastic won't melt fast enough.
This leads to:
Underextrusion: Gaps in print walls or infill.
Extruder Skipping: The extruder motor clicks because it cannot push the solid filament through the nozzle.
Weak Layer Adhesion: The plastic is extruded too cold to bond properly.
Typical Max Flow Rates by Hotend Type
Use the calculator above to check if your settings are within safe limits. Compare your result to these general benchmarks:
Hotend Type
Approx. Max Flow Rate (PLA)
Target Use Case
Standard V6 / Mk3s
10 – 15 mm³/s
General printing, fine detail
High Flow (e.g., Dragon HF)
20 – 24 mm³/s
Faster printing speeds
Volcano / CHT Nozzle
25 – 45+ mm³/s
Large parts, very high speed
Super Volcano / Goliath
80+ mm³/s
Large format industrial
How to Use This Information
If you are tuning your slicer (like Cura, PrusaSlicer, or OrcaSlicer) for speed, you should find your hotend's limit first. Once you know your hotend caps out at, for example, 15 mm³/s, you can input this into the "Max Volumetric Speed" setting in your slicer. The software will then automatically throttle your print speed for thicker layers or wider lines to ensure you never exceed that melting limit.
function calculateFlowRate() {
// Get input values using var
var layerHeight = document.getElementById('layerHeight').value;
var lineWidth = document.getElementById('lineWidth').value;
var printSpeed = document.getElementById('printSpeed').value;
var filamentDiameter = document.getElementById('filamentDiameter').value;
// Parse values to floats
var lh = parseFloat(layerHeight);
var lw = parseFloat(lineWidth);
var ps = parseFloat(printSpeed);
var fd = parseFloat(filamentDiameter);
// Validation
if (isNaN(lh) || isNaN(lw) || isNaN(ps) || lh <= 0 || lw <= 0 || ps 0) {
feedSpeed = flowRate / filamentArea;
}
// Display Results
var resultContainer = document.getElementById('vfrResult');
var flowResultDisplay = document.getElementById('flowResult');
var feedResultDisplay = document.getElementById('feedResult');
var warningDiv = document.getElementById('hotendWarning');
resultContainer.style.display = "block";
flowResultDisplay.innerHTML = flowRate.toFixed(2) + " mm³/s";
feedResultDisplay.innerHTML = feedSpeed.toFixed(2) + " mm/s";
// Logic for warnings based on standard hotend capabilities
// Standard V6 usually caps around 15, High flow around 25, Volcano around 35+
var warningMsg = "";
if (flowRate > 15 && flowRate <= 25) {
warningMsg = "Note: This flow rate exceeds the capabilities of most standard hotends (like stock Ender 3 or Mk3). You may need a High-Flow hotend or CHT nozzle.";
warningDiv.style.backgroundColor = "#fff3cd"; // Yellow
warningDiv.style.color = "#856404";
warningDiv.style.borderColor = "#ffeeba";
} else if (flowRate > 25) {
warningMsg = "High Flow Alert: This requires a dedicated high-flow setup (Volcano, Rapido, etc.). A standard hotend will likely clog or skip steps.";
warningDiv.style.backgroundColor = "#f8d7da"; // Red
warningDiv.style.color = "#721c24";
warningDiv.style.borderColor = "#f5c6cb";
} else {
warningMsg = "Good: This flow rate is within the safe range for most standard 3D printers.";
warningDiv.style.backgroundColor = "#d4edda"; // Green
warningDiv.style.color = "#155724";
warningDiv.style.borderColor = "#c3e6cb";
}
if (warningMsg !== "") {
warningDiv.innerHTML = warningMsg;
warningDiv.style.display = "block";
} else {
warningDiv.style.display = "none";
}
}