Bühlmann Deco & Gas Planner
Plan no-stop and decompression schedules using the Bühlmann ZHL-16C model with Gradient Factors, and estimate gas consumption by cylinder. Configure bottom and deco cylinders, RMV/SAC, and water type; the planner simulates inert gas loading and provides suggested stops, runtimes, and per-cylinder gas usage for turn and reserve planning.
Disclaimer: For education and planning practice only. Do not use as the sole source for dive planning or execution. Always follow your training and rely on a manufacturer-rated dive computer and validated tables.
How to use the Bühlmann deco planner
Enter your planned depth and bottom time, then set up the cylinders you're carrying — bottom gas and any deco gases, with their O2 and He fractions, cylinder type, and starting pressure. Set your descent/ascent rates, Gradient Factors (GF Low / GF High), and maximum deco PO2 to match your own planning standards.
Diving a rebreather instead of open circuit? Switch on CCR mode to plan around setpoints and a diluent mix rather than a fixed bottom-gas percentage.
The planner returns a full runtime schedule with stop depths and durations, gas switches, and estimated CNS%/OTU oxygen exposure for the dive, plus a gas plan showing how much of each cylinder you're expected to use based on your SAC rate — useful for checking your plan against rule-of-thirds or your own reserve policy before you dive it.
FAQ
What is the Bühlmann algorithm?
The Bühlmann decompression model (ZHL-16, and its later ZHL-16C revision) is one of the most widely used decompression algorithms in both dive computers and planning software. It models the body as 16 theoretical tissue compartments, each absorbing and releasing inert gas at a different rate, then works out the shallowest depth (the 'ceiling') you can ascend to at each point in a dive without exceeding a safe tissue gas loading.
What are Gradient Factors (GF Low / GF High)?
Gradient Factors add a safety margin on top of the raw Bühlmann ceilings. GF Low controls how conservative your first stop is (lower = deeper, more conservative first stop), and GF High controls how conservative your final ascent to the surface is (lower = more conservative). This calculator defaults to GF 50/70, a moderately conservative setting common in technical diving — adjust both to match your own training and comfort.
Can I plan a rebreather (CCR) dive with this calculator?
Yes — enable CCR mode to plan around fixed setpoints instead of open-circuit gas mixes. You can set a low and high setpoint, the depth where you switch between them, and a separate deco setpoint and switch depth, along with your diluent mix.
Is an online Bühlmann calculator accurate enough to dive with?
This tool is for education and planning practice, not as your sole source of dive planning. Always cross-check any schedule against your training and a manufacturer-rated dive computer or dedicated planning software before diving it.