Volumetric Flow Rate Calculator

Calculate the volumetric flow (mm³/s) required for your print settings to ensure you don't exceed your hotend's melting capacity.

Note: Max flow depends on your hotend and filament material. PLA flows freely at 15 mm³/s on a V6, but PETG may max out around 8 mm³/s on the same hotend. Use the reference tables below for guidance.

Print Settings

Layer Height (mm)

Line Width (mm)

Print Speed (mm/s)

Hotend Limit

Max Hotend Flow (mm³/s)

Quick-set:

Volumetric Flow

Required Flow

8.80 mm³/s

Within limit (15 mm³/s)

Hotend Utilization59%

Max Speed at These Settings170.5 mm/s

Printing faster than your hotend can melt filament causes under-extrusion, extruder clicking, and weak parts.

How Volumetric Flow Works

Volumetric flow rate is the volume of molten plastic your hotend must push through the nozzle every second, measured in mm³/s. It is determined by three settings:

Flow = Layer Height × Line Width × Print Speed

Every hotend has a maximum flow rate — the fastest it can melt and extrude filament. This limit depends on the heater block length, nozzle geometry, heater power, and the filament material's melt characteristics. If your print settings demand more flow than the hotend can deliver, the extruder cannot push filament fast enough and you get under-extrusion.

Reference Values

By Hotend (PLA, 0.4 mm nozzle)

Hotend	Max Flow
E3D V6 / Revo Six	15 mm³/s
E3D Volcano	25 mm³/s
Bambu Lab (stock 0.4 mm)	21 mm³/s
Bambu Lab (high-flow 0.4 mm)	32 mm³/s
Creality Spider / K1	32 mm³/s
Slice Mosquito	20 mm³/s

Practical safe values with 0.4 mm brass nozzle at typical temperatures. Larger nozzles and higher temps increase these numbers.

By Material (V6-class hotend)

Material	Max Flow	Note
PLA	15 mm³/s	Easy to melt, highest flow
ABS / ASA	11 mm³/s	Higher temps, moderate flow
PETG	8 mm³/s	Viscous melt, lower flow
TPU	3.5 mm³/s	Flexible, very slow
Nylon (PA)	8 mm³/s	Similar to PETG
PC (Polycarbonate)	8 mm³/s	High viscosity

Based on Prusa Knowledge Base recommendations. Your actual limit may differ — always test with your specific setup.

Tips & Troubleshooting

Signs of Exceeding Flow Limit

Clicking or grinding from the extruder, missing layers or patchy infill at high speeds, and parts that are weaker than expected. If slowing the print fixes the issue, your flow rate was too high.

Use Your Slicer's Limit

PrusaSlicer, OrcaSlicer, and Bambu Studio all have a "Max Volumetric Speed" setting in the filament profile. Set it to your hotend's limit and the slicer will automatically slow down when needed — no manual speed tuning required.

CHT & High-Flow Nozzles

Bondtech CHT nozzles split the filament into 3 channels inside the nozzle, increasing the melt surface area. They typically boost flow by 30–60%, and can nearly double it on longer melt zones like the Volcano.

Temperature Matters

Printing at higher temperatures lowers filament viscosity and can increase max flow. For example, PLA at 230 °C will flow faster than at 200 °C — but too high risks stringing and heat creep. Find the balance for your setup.

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