Gradient Factors (GF) and dive computers

Reduction Factor (RF) or Gradient Factors (GF) are coefficients (e.g. 90%, 80%...) that can only be used with Haldanian sets of parameters (e.g. U.S. Navy, Bühlmann...) and that allow the M-Values to be reduced in order to increase the duration of stops (or reduce the limit of no-stop dives) and, depending on the case, their depth.

They have been used in virtually all dive computers for over 30 years, with built-in pre-setting. Some recent models of dive computer, based on technical diving, have left their settings free. This means that users need to know how to set them.

This CMAS factsheet provides recommendations and full explanations: https://www.cmas.org/resources/fact-sheets.html