Decompression Dive Planner

Dive Planner — Key Features

• Bühlmann ZH-L16C decompression algorithm with 16 tissue compartments
• Open Circuit and CCR (Closed Circuit Rebreather) dive planning
• Multi-gas planning with automatic deco gas switching
• CCR setpoint management, diluent configuration, and equivalent gas modeling
• Bailout planning with stress factor and OC emergency gas analysis
• Configurable gradient factors (GF Low / GF High) with 6 presets and custom values
• Detailed ascent profile with runtime, gas consumption, and safety metrics
• CNS/OTU oxygen toxicity tracking and gas density warnings

Dive Planner — How It Works

Set your maximum depth, bottom time, and gas mix. Choose Open Circuit or CCR — for CCR, configure setpoints, diluent, and O₂/diluent tanks. The planner runs the Bühlmann ZH-L16C decompression model, tracking inert-gas tension across 16 theoretical tissue compartments (half-times from 4 to 635 minutes). For CCR, equivalent-gas modeling converts your loop ppO₂ into the inspired mix at each depth so deco obligations stay realistic. Gradient factors (GF Low / GF High) tune your conservatism: a lower GF Low pulls first stops deeper to crush bubbles before any insult; GF High at 100% would track the original Bühlmann M-values. Add deco gases for optimised off-gassing, enable bailout planning to verify emergency reserves in loss-of-loop scenarios, and watch CNS%, OTU, gas density, and runtime update live as you adjust parameters. The planner is a teaching and pre-dive planning aid — always cross-check with your dive computer and team brief before splashing.

Why Use Our Dive Planner?

• Based on the Bühlmann ZH-L16C algorithm — the gold standard in decompression planning
• Full CCR rebreather support with setpoints, equivalent gas modeling, and bailout planning
• Supports air, nitrox, trimix, and heliox gas mixes
• Save and share dive plans with your buddy or instructor
• Works on any device — desktop, tablet, or mobile

Dive Planner — Frequently Asked Questions

What algorithm does the dive planner use?

The DiveToolbox planner uses the Bühlmann ZH-L16C decompression algorithm with configurable gradient factors. ZH-L16C tracks inert-gas saturation across 16 theoretical tissue compartments with half-times from 4 to 635 minutes, computing tolerable ascent ceilings at each step. Gradient factors (Baker 1998) let you tune conservatism: a low GF Low pulls first stops deeper to reduce bubbles, while GF High sets shallow-stop aggressiveness. The same model powers most modern dive computers — DiveToolbox uses standard implementations cross-verified against reference algorithms.

Can I plan multi-gas dives?

Yes — the planner supports unlimited gas switches across Open Circuit air, nitrox, and trimix. Add bottom gases, travel gases, and decompression gases at the depths and times you plan to switch them. The algorithm computes optimum off-gassing with each new gas, accounting for the change in inert-gas fractions and oxygen partial pressure. CCR mode adds bailout-gas planning so you can verify reserves under loss-of-loop scenarios. Switches are validated against MOD limits at the configured ppO₂ ceiling.

What are gradient factors?

Gradient factors (GF) are tunable conservatism parameters introduced by Erik C. Baker in 1998 to modify Bühlmann's M-values — the maximum tolerated inert-gas tension per tissue compartment. GF Low is the fraction of the M-value gradient you accept at the first stop (lower = deeper first stop to crush bubbles early); GF High is the fraction accepted at the surface (lower = more shallow stops). Common presets balance the two: 30/70 is conservative, 40/85 is the de-facto recreational-tech default, 50/85 is aggressive. Use the [Gradient Factors](/en/gradient-factors) tool to visualise the trade-off.

How deep can I plan dives?

The planner accepts depths up to 200 metres / 656 feet for technical trimix dives. Beyond about 60 m on air, narcosis and gas density become limiting — at that point the planner expects helium in the mix and will flag MOD and density warnings. Practical depth ceilings depend on your training, equipment, and team: most recreational training agencies cap at 30-40 m, technical agencies extend to 100+ m with appropriate certification. Always plan within your training, not the tool's mathematical range.

Can I export or share my dive plan?

Yes — dive plans can be exported as PDF (with full deco schedule, gas usage, CNS/OTU, gradient factors, and notes) and shared via private URL. The PDF format suits printing for boat briefings or saving offline; the share link lets a buddy or instructor review the plan in their browser without an account. Shared plan pages are noindex by default so user-generated content does not leak into search results. PDF export uses jsPDF and is fully client-side — no plan data leaves your browser unless you choose to share.

What safety stops does the planner include?

The planner automatically includes a 3-minute safety stop at 5 metres (15 feet) on no-decompression dives and adds Bühlmann-required deco stops on dives that exceed NDLs, in 3-metre / 10-foot increments from the first stop up to the surface. Stop times reflect the chosen gradient factors. You can disable the safety stop for short, shallow dives where it adds no value, or extend stops manually to add personal conservatism — common practice on hard dives, cold dives, or after long surface intervals between days.

Does the dive planner support CCR (rebreather) diving?

Yes — CCR mode supports any setpoint (commonly 1.2-1.3 ata for bottom, 1.4 for deco), any diluent (air, trimix, heliox), and an independent O₂/diluent tank pair for bailout planning. The model uses equivalent-gas mathematics: at every depth the algorithm computes the actual inspired mix from your loop ppO₂ and diluent, then tracks tissue saturation as if you were breathing that mix open-circuit. This is the same approach used by Shearwater Petrel, JJ-CCR, and most modern tech-rebreather computers — outputs cross-verify within seconds.

→ How to Plan a Trimix Dive — A 6-step workflow connecting every calculator in the right order

→ Diving Glossary — Essential acronyms and concepts every diver should know