How the math works
The calculator first finds the total length of the extruded plastic path. It does this by converting your model's volume into the volume of a long, thin line, using your layer height and nozzle width as the line's cross-section (Extruded Length = Model Volume / (Layer Height × Nozzle Width)). It then divides this path length by your average print speed to get the raw extrusion time. Finally, it adds the user-defined time margin to account for non-printing moves and acceleration changes.
Frequently Asked Questions
Why is this different from my slicer's estimate?
Your slicer (Cura, PrusaSlicer, etc.) has a complete physics model of your printer, including acceleration, jerk, and specific speeds for infill, walls, and travel. This tool uses a simplified model with an "average" speed. It's best used for quick comparisons (e.g., "how much time would a 0.6mm nozzle save me?") without needing to re-slice every time.
What's a good "Average Print Speed" to enter?
Look at your slicer's speed settings. A good starting point is to average your main "Infill Speed" and "Wall Speed". If you print at 50mm/s for walls and 80mm/s for infill, a value of 60-65 would be a reasonable average to enter here.
What should I set for the time margin?
20-30% is a good starting point for most models. A simple, solid model with little travel (like a cube) might be closer to 15%. A complex model with many separate parts or thin features that require a lot of travel and retractions could be 40% or higher. This is the "fudge factor" that accounts for all non-extrusion time.