I am sharing this excellent article by ‘Doppler’ as it really covers the essentials of understanding Gradient Factors in modern Buhlmann decompression algorithms.  In conjunction with Eric Baker’s ”Understanding M-Values’, this forms essential reading for any advanced diver seeking to utilize Buhlmann GF on their dive planning software, or technical diving computers like the Petrel or XDeep.


All dives are decompression dives, ergo all divers are decompression divers. Our acknowledgement of this and the depth of that acknowledgement can greatly influence our behavior when we dive: most specifically, our ascent behavior. How deep we dive, what gases we breathe, and how long we spend at depth vary considerably from dive to dive; but all dives share one common threat for individual divers: the risk of getting bent.

gradient factors buhlmann decompression


Smart divers consider many factors when planning dives, many of which help to alleviate that risk. One is choosing to dive a “conservative profile.” I guess there are many interpretations of what that means… but for our purposes here, it means choosing a decompression algorithm that’s proven, and choosing a setting for that algorithm that will generate stress-tolerant dive tables.

Many PDC (personal dive computers) use a Bühlmann ZHL-8 or ZHL-16 algorithm to model decompression stress in divers and their decompression obligation on ascent.

To continue reading, please visit Doppler’s blog at: Gradient Factors, A Simplified Primer

What Others Are Reading