Because the estimate assumes the printer reaches its planned speeds, and in practice acceleration limits, firmware settings, heating time, filament changes and pauses slow it down. The gap is usually largest on small, detailed parts and multicolour prints.
A slicer’s time estimate is a calculation from the planned moves, and the printer does not always move as planned.
Where the time goes
Acceleration: on short moves the toolhead never reaches its planned speed. Firmware limits: the printer may cap speed or acceleration below the slicer’s values. Heating: warming the bed and nozzle before the print, and after filament changes. Filament changes and purges on multicolour systems. Calibration routines such as levelling before each print.
Parts that widen the gap
Small parts with many short moves, detailed surfaces, lots of retractions and printed supports all reduce average speed below what the estimate assumes.
Making estimates closer
Use the printer maker’s profile, which carries its real limits. Keep firmware and slicer versions aligned with the maker’s recommendations. Compare a few finished prints with their estimates to learn the usual ratio for that printer.
What the listing speed has to do with it
Very little. A published maximum speed describes the motion system, and a print time depends on the file, the material and the settings in use.
If this page and the manufacturer’s manual disagree, follow the manual. Every laser power, speed, build volume, resolution, temperature and safety rating on this page is taken from the maker’s own documentation, with its unit as published and its source named — none of it is measured here. A figure is written the way the maker states it and is not converted into another convention, because the converted value would be a different number. And for any print speed: a published maximum speed describes what the motion system can reach, not how fast a good part is printed. The speed that works depends on the material, the geometry, the cooling and the slicer profile. This page quotes the maker’s figure as a maximum and draws no print time from it.
Questions makers ask before buying
Can the estimate be made more accurate?
Using the printer maker’s own profile, with its acceleration and speed limits, makes the estimate closer. Some slicers also account for firmware limits more precisely than others.
Why do multicolour prints take so much longer?
Each colour change unloads and loads filament and purges the old colour, which adds time and material to every layer that uses more than one colour.
Last reviewed 15 September 2026