Pressure advance & linear advance calculator

Pressure advance compensates for the pressure lag inside the melt zone — it is what makes corners sharp instead of bulged. Tune extrusion first with the rotation distance calculator, and if you are pushing speed, check the volumetric flow calculator too.

How to use — Klipper tower method

Slice a tall, hollow square test tower and step pressure advance as it prints (the Klipper pressure advance guide shows the tower and the SET_PRESSURE_ADVANCE stepping). Bowden setups typically use factor = 0.005 from a start of 0, direct drive 0.02. When done, find the height where the corners look cleanest, measure it from the bottom with calipers, and enter it here. The result is PA = start + height × factor. Paste the config line under [extruder] in printer.cfg and issue a RESTART.

How to use — Marlin linear advance

Marlin's K value cannot be derived from a tower measurement, so this page gives you a consensus starting point instead. Typical ranges:

• Direct drive — K 0.02–0.08 (very short filament path, little lag).
• Bowden — K 0.3–1.0+ (long tube, lots of compression to absorb).

These are honest starting points, not answers — K depends on material, temperature and speed, so a physical calibration print (Marlin's K-factor pattern) is always required. Linear advance must be compiled in (LIN_ADVANCE); set the value with the M900 line shown and save with M500. Note that some slicers emit their own M900 and will overwrite your value.