Gradient factors (GF Low / GF High)

Gradient Factors define how much nitrogen stays in your tissues during ascent. They manage the ratio between your actual tissue pressure and the ambient pressure. Divers use these numbers to customize deco profiles on computers like the Shearwater Perdix. Typical settings are 30/70 or 50/80. A low GF number controls the first stop. A high GF number controls the final ascent to the surface.

Many divers pick a 30/70 setting because it keeps deep stops conservative. This can increase your total deco time by 15% in some profiles. I saw a diver in Komodo in 2019 use a 10/70 setting. That choice made his deco much longer than necessary. Always check your settings before you enter the water. Do not rely on default factory values alone.