What decides how long a print takes
Prusa’s knowledge base names layer height as the main factor in print time. Taller layers shorten a print a lot, at the cost of more visible lines. Thin layers such as 0.10 mm add detail and take longer. Prusa does not suggest going thinner than that, because 0.07 or 0.05 mm layers add little quality for much more time.
The amount of plastic counts next, because a bigger model or more infill means more grams to lay down. Prusa says infill affects the speed of printing, and that most models print fine with 10 to 15% of it.
How long our prints took
On our X2D, nine prints of PLA and PETG from 0.4 g to 141 g took between 8 minutes and 5 hours, from start to finish. The four prints above 50 g ran at 28 to 38 g an hour. Parts from 3 g to 30 g ran at only 14 to 19 g an hour, and a 0.4 g part took 8 minutes. Small parts take longer for their size, so a time scaled down from a big print comes out too short.
Each print ended within 10% of the time that Bambu Studio estimated, from 7.7% sooner to 9.5% later. Added up, the nine took 14.9 hours, the same as their estimates.
How the calculator estimates
It takes the pace of a print you made, its grams over its time, and gives the new print the same pace. A 150 g print at the pace of 62 g in 1 h 37 min takes about 3 h 55 min.
When the new print uses another layer height, the calculator also scales the time by the ratio of the two heights. At the same speeds, a layer half as tall lays down half the plastic each second. That part is a rough rule rather than a measurement. Once you slice the model, the slicer’s time is better than any estimate.
Make a print faster
Taller layers save the most time. PrusaSlicer’s variable layer height prints thin layers only where the shape needs them, which Prusa says can cut a lot of time with little loss of quality. Less infill saves time too, and Prusa says you will rarely need more than 30%.
Print time also costs money in power and in wear on the printer. The 3D print pricing calculator takes the hours of a print and adds both to the cost of the filament.