Pressure advance is a firmware or slicer control feature used in FDM 3D printing to compensate for the delay between filament movement and actual nozzle pressure. When a printer accelerates, the nozzle can briefly under-extrude; when it slows down, it can over-extrude. Pressure advance adjusts extrusion flow during these transitions so corners stay sharper and line width remains more consistent.
This matters because many print defects come from changing speed, not just bad temperature or calibration. In practice, pressure advance is tuned per printer, nozzle, filament, and sometimes even print speed. Used well, it improves dimensional accuracy, reduces blobs and gaps, and makes fast printing more reliable. Used poorly, it can create thin walls, rough edges, or inconsistent layers.