Extrusion flow ratio (flow_ratio)
Extrusion flow ratio is a multiplier, where 1 leaves the value alone. The material may have volumetric change after switching between molten state and crystalline state.
What does each slicer call it?
Five slicers, five spellings of one setting. The scope column is which preset the key belongs to, which is what decides whether changing it follows the printer, the filament, or the print profile.
| Slicer | Key | Scope |
|---|---|---|
| PrusaSlicer | extrusion_multiplier |
filament |
| Bambu Studio | filament_flow_ratio |
filament |
| OrcaSlicer | filament_flow_ratio |
filament |
| Cura | material_flow |
filament |
| Creality Print | filament_flow_ratio |
filament |
Where does it live in the file?
All five slicers file this under the filament preset, so its value follows the filament rather than the model. A .3mf is a zip, so unzip it and search for extrusion_multiplier, filament_flow_ratio and material_flow, or open the file in preslice and read the Raw tab, which searches every member at once.
Four of the five slicers write their settings into a sidecar part beside the geometry. Cura writes them into the model XML itself, so there is no config part to open.
| Slicer | Part | Format |
|---|---|---|
| PrusaSlicer | Metadata/Slic3r_PE.config |
INI, one key = value per line |
| Bambu Studio | Metadata/project_settings.config |
JSON, one flat object |
| OrcaSlicer | Metadata/project_settings.config |
JSON, one flat object |
| Cura | 3D/3dmodel.model |
XML metadata inside the model part, under a cura namespace |
| Creality Print | Metadata/project_settings.config |
JSON, one flat object |
What values are valid?
Each slicer declares its own type, default, and bounds for its key. They do not always agree, and where they disagree the file is still valid in both: the slicer that wrote it is the one that enforced its own rule.
| Slicer | Type | Unit | Default | Range |
|---|---|---|---|---|
| PrusaSlicer | float | not declared | 1 |
2 or less |
| Bambu Studio | floats | not declared | not declared | 2 or less |
| OrcaSlicer | floats | not declared | not declared | 0 to 2 |
| Cura | float | % | 100 |
not declared |
| Creality Print | floats | not declared | not declared | 2 or less |
Cura declares no range for this key, so nothing in the file bounds it.
PrusaSlicer, Bambu Studio, OrcaSlicer and Creality Print declare no unit for it either, so the bare number is read as a multiplier, where 1 leaves the value alone.
The slicers disagree on the type: PrusaSlicer and Cura as float, Bambu Studio, OrcaSlicer and Creality Print as floats. preslice reads all of them.
Every type, default, and bound above is read from the slicer's own field definitions rather than from measurement: PrusaSlicer's PrintConfig.cpp, Bambu Studio's PrintConfig.cpp, OrcaSlicer's PrintConfig.cpp, Cura's fdmprinter.def.json and Creality Print's PrintConfig.cpp.
Can I read it from my own file?
Yes, without installing a slicer. Open preslice and drop a .3mf on the page. It unzips and parses the file in your browser, and shows extrusion flow ratio under its own name alongside the rest of the print settings. The file never leaves your machine, and nothing uploads.