Estimate filament extrusion flow using a rectangular bead: line width × layer height × print speed. Enter your own maximum volumetric flow to calculate the corresponding flow-limited speed. Defaults are illustrative, not a rating for your printer.
Enter dimensions in mm, print speed in mm/s and maximum flow in mm³/s. Use extrusion line width, which may differ from nozzle diameter.
The bead is treated as a rectangle with constant width and height. Real extrusions have rounded cross-sections, and slicer geometry models can produce different results. This estimate excludes extrusion-multiplier corrections and transient pressure effects. The speed equation follows the practical relationship described in Ellis’ Print Tuning Guide.
Utilization above 100% means the estimated demand exceeds your entered flow limit. At 100%, demand equals that limit under this approximation. Zero print speed gives zero estimated flow.
The arithmetic uses numerical magnitudes in the displayed units: width divided by 1 mm, height divided by 1 mm, speed divided by 1 mm/s and maximum flow divided by 1 mm³/s. These normalized values are dimensionless scalars; results are interpreted in the units shown in their labels. No automatic conversion from other input units is performed.
The calculated speed is a flow-based ceiling, not a promise that the printer can reach it. Motion speed limits, acceleration, short paths, cooling and print-quality settings can require a lower speed. Travel moves without extrusion do not demand this bead flow.
Maximum usable flow depends on the hotend, nozzle, material and printing conditions. Enter a value established for your setup rather than treating the example default as a specification. See Prusa’s maximum volumetric speed explanation.
Accepted ranges are 0.01–5 mm line width, 0.01–3 mm layer height, 0–2000 mm/s print speed and 0.01–1000 mm³/s maximum flow. These are calculator bounds, not recommended printer settings. Choose a physically appropriate width and height for your nozzle and profile; independent bounds do not validate their combination.
Positive width and height prevent division by zero. Maximum flow must be positive for utilization to be defined. An unavailable result indicates an invalid or out-of-range calculation and must not be interpreted as zero.
| Line width | Layer height | Print speed | Entered maximum flow | Estimated flow | Speed at maximum flow | Utilization |
|---|---|---|---|---|---|---|
| 0.45 mm | 0.20 mm | 100 mm/s | 12 mm³/s | 9 mm³/s | 133.33 mm/s | 75% |
| 0.60 mm | 0.30 mm | 100 mm/s | 15 mm³/s | 18 mm³/s | 83.33 mm/s | 120% |
| 0.45 mm | 0.20 mm | 0 mm/s | 12 mm³/s | 0 mm³/s | 133.33 mm/s | 0% |
For the first example, bead area is 0.45 × 0.20 = 0.09 mm². At 100 mm/s, flow is 0.09 × 100 = 9 mm³/s. With an entered limit of 12 mm³/s, the flow-limited speed is 12 ÷ 0.09 ≈ 133.33 mm/s.
In the second example, 18 mm³/s exceeds the entered 15 mm³/s limit. Holding width and height constant, reducing speed to approximately 83.33 mm/s brings the estimate to that limit.
Formula sources
- Ellis’ Print Tuning Guide — Determining Maximum Volumetric Flow Rate; relationship between line width, layer height, flow and print speed.
- Prusa Knowledge Base — Max volumetric speed; volumetric limits and their effect on extrusion speed.
Artwork creation required before activation: create and register a 400 × 400 pixel WebP thumbnail, then insert it as the first image block using its registered asset ID. No suitable registered asset was supplied. Match neighboring thumbnails: a cheerful yellow five-point star with hands, floating without separate legs or feet, on white with playful navy, blue and teal extrusion graphics. Inspect neighboring thumbnails before creating the artwork.