This tool estimates the panning speed where judder will likely become too pronounced. The goal is to provide a more accessible tool than the charts and tables commonly referenced in cinematography manuals. It uses the standard rule of thumb that camera panning should not cause objects to transit the entire horizontal extent of an image in any less than seven seconds.
However, results should only be taken as a rough guide; images will not immediately become unwatchable faster than specified, nor will they become fully artifact-free when panning slower than this limit.
Ultimately though, a human is watching the panning, and what matters is whether the panning looks good to them. Any results should also fit the mood and content of the scene. High energy or low contrast scenes can often get away with more abrupt camera movements, for example. However, what feels too fast to one person may feel just right to another, so having an objective baseline is key.