Flow & Nozzle Calculators
Volumetric Flow Calculator
Calculate volumetric flow demand in mm3/s from nozzle line width, layer height, and print speed, then compare it to your hotend's maximum volumetric flow.
Results update below from browser-local calculations.
Breakdown
| Volumetric flow | 0 |
|---|
How to Use This Calculator
- Enter your nozzle line width (often close to nozzle diameter), the layer height, and the print speed you want to run.
- Read the volumetric flow demand in cubic millimeters per second.
- Compare it to your hotend's tested maximum volumetric flow to see whether the speed is realistic.
Inputs and Assumptions
| Line width or nozzle diameter | Use slicer line width for better accuracy. 0.4 mm is only a default proxy. |
|---|---|
| Layer height | Enter this value in mm. |
| Print speed | Enter this value in mm/s. |
Volumetric flow example
A 0.45 mm line width at 0.2 mm layer height and 150 mm/s needs about 13.5 mm3/s. A typical stock hotend tops out near 10-12 mm3/s, so that speed would under-extrude unless the hotend can keep up.
What Volumetric Flow Means
Volumetric flow is how much molten plastic the hotend must melt and push every second, measured in cubic millimeters per second. It is the best way to compare speeds across different nozzles and layer heights.
The formula is line width x layer height x print speed. Doubling the layer height or the speed roughly doubles the demand.
Demand vs Hotend Limit
Every hotend has a maximum volumetric flow it can sustain before it under-extrudes, often 8-12 mm3/s for stock setups and 20-30+ mm3/s for high-flow hotends.
If your calculated demand is higher than the tested limit, lines will be thin and weak no matter what speed the slicer reports. Lower the speed, the layer height, or the line width, or use a higher-flow hotend.
How to Find Your Hotend Limit
- Print a flow-rate test that increases volumetric flow step by step at a fixed temperature.
- Watch for the point where the extruder skips or the surface turns rough and under-extruded.
- Record a safe limit slightly below that failure point and reuse it as your maximum.
- Higher temperatures usually allow more flow, within the filament's safe range.
Turn Flow Into a Speed Limit
Once you know your hotend's maximum volumetric flow, the nozzle speed calculator works backward to a safe maximum print speed for a given line width and layer height.
Formula
Volumetric flow = nozzle diameter × layer height × print speed. This uses nozzle diameter as a simple line-width proxy.
Limits of This Calculator
- This estimates demand, not your hotend's capability. Find the real limit with a flow test such as a temperature-vs-flow tower.
- Line width, not just nozzle diameter, drives the result. Wider lines and thicker layers raise demand quickly.
- Acceleration and travel mean real prints rarely hold peak speed, so treat the number as a worst case.
FAQ
Is nozzle diameter the same as line width?
Not always. This simple calculator uses nozzle diameter as the default proxy.
Does this know my hotend limit?
No. Enter your known max flow in the nozzle speed calculator.
What is a typical maximum volumetric flow?
Stock hotends often sustain about 8-12 mm3/s, while high-flow hotends can reach 20-30 mm3/s or more. Always confirm your own limit with a flow test instead of trusting a specification.
How do I lower volumetric flow demand?
Reduce print speed, layer height, or line width. Any of these lowers how much plastic the hotend must melt each second.
Is volumetric flow the same as print speed?
No. Print speed is how fast the nozzle moves, while volumetric flow is how much plastic must be melted per second. The same speed needs more flow at a thicker layer height or wider line width.