Plan Your Dive in
Two Minutes.
On Any Device.
DiveCommand is the dive planner you’ll actually use before every dive — fast, browser-based, works offline, and runs the exact same Bühlmann ZHL-16C algorithm as your Shearwater, Garmin, and Suunto. No install. No account. No excuses.
Three Problems. One Tool.
Most dive planning software has at least one of these problems. DiveCommand was built specifically to solve all three.
The best dive plan is the one that happens. Open a browser, pick depth and gas, read your NDL — that’s the whole workflow. No install, no account, no app to update. Fast enough that skipping it stops making sense. Works on your phone at the dive site, laptop at home, tablet on the boat.
If your planner and your dive computer give different NDLs, one of them is wrong. DiveCommand uses the exact ZHL-16C at GF 40/85 — the same values Shearwater, Garmin, and Suunto ship with. Verified across 12,067 tests. The numbers match because the math is identical.
Swap gas — NDL extends, ppO₂ updates, MOD recalculates. Adjust GF Low — tissue ceilings shift. Change depth — all 16 compartments respond. Every variable is live. No recalculate button. Plan the dive interactively, not by filling out a static form.
Planning That Takes
Two Minutes, Not Twenty.
Select depth and gas. DiveCommand immediately returns your NDL, ppO₂, and CNS O₂ — calculated across all 16 Bühlmann ZHL-16C tissue compartments simultaneously. The tissue bars update as you change any input. No waiting. No recalculate button. Just answers.
Adjust gradient factors and watch ceilings shift. Switch from air to EAN32 and see the NDL extend. Move to trimix — EAD, END, ENP, and Z-factor real gas values recalculate instantly. Every variable is live. Change anything, read the result, and go dive.
The Δ=0 badge is the result of a Python reference implementation written from scratch and tested against the JavaScript engine at every depth and gas combination. 12,067 independent tests. Zero failures. So when your NDL matches your Shearwater, it’s not a coincidence — it’s the math.
If Your Computer Runs It, DiveCommand Matches It
Bühlmann ZHL-16C at GF 40/85 is the factory default on every major dive computer. DiveCommand uses the same constants, compartment half-times, and gradient factor implementation.
Δ=0 means zero deviation in NDL and decompression ceiling at factory default GF settings. Verified using an independent Python implementation with a completely separate codebase — not self-comparison. The validation harness is a public self-contained HTML file. Open it and run the tests yourself.
Altitude Corrections.
One Tap.
Diving at elevation — a mountain lake, a high-altitude reservoir, anywhere above sea level — changes every calculation you make. Reduced atmospheric pressure lowers M-values in every tissue compartment, which shortens NDLs. Same depth, same gas, shorter no-stop time. Anyone planning without altitude correction is working from optimistic numbers.
DiveCommand handles it automatically. Set your elevation and every NDL, ppO₂, and decompression obligation recalculates instantly — no conversion tables, no manual offset. The correction is built into the core ZHL-16C calculation, not a post-processing adjustment.
Covers sea level through 11,000ft with common elevation presets. If you dive in the mountains, it just works.
Correction (ft)
On Elevation Select
a Lookup Table
Presets Built In
From First Reef Dive to 330ft Trimix Profile
The same validated engine scales from a single recreational no-stop dive to a multi-gas technical decompression profile.
All 16 Bühlmann tissue compartments running simultaneously — 5-minute fast tissues through 635-minute slow tissues. GF 40/85 factory defaults match Shearwater, Garmin, and Suunto exactly. Adjust GF Low and GF High independently. Tissue bars update in real time as you change any parameter.
✓ Δ=0 · ZHL-16C · GF 40/85Full technical gas planning to 330 feet. EAD, END, ENP, and Z-factor real gas corrections for high-pressure helium mixtures. Custom GF presets for different profile types. Three-bottle stage/deco gas management with rock bottom calculator.
✓ Trimix · EAD · END · ENP · Z-factorSea level through 11,000ft with common elevation presets. Every NDL, ppO₂, EAD, END, and deco ceiling recalculates instantly on elevation change. Integrated into the core ZHL-16C calculation — not a post-processing table — so every tissue compartment reflects the correct ambient pressure.
✓ Auto-Corrected · Sea Level to 11,000ftToggle gas and watch ppO₂, MOD, CNS O₂, and tissue loading update simultaneously. ppO₂ hard limit enforcement at 1.4 and 1.6 ata. CNS clock tracks cumulative oxygen toxicity. Visual warnings before any limit is approached.
✓ ppO₂ · MOD · CNS O₂ · LiveLog every dive with site, buddy, depth, bottom time, gas, temp, and visibility. SAC rate tracking across dives and conditions. Plan vs actual comparison. CSV export for records or training review.
✓ SAC Rate · Plan vs Actual · CSVLiveaboard expedition planning. Tissue loading carries forward from dive to dive across multiple days. The tissue state at the end of Day 2 Dive 4 is the starting point for Day 3 Dive 1. No manual resetting — the model tracks your actual nitrogen load continuously.
✓ Multi-Day · Expedition PlanningClean print-ready plan showing profile, NDLs, gas switches, CNS budget, and deco schedule. SVG dive profile visualization with tissue compartment loading overlay. Fully self-contained — no internet needed to view a printed plan.
✓ SVG Profile · Print-ReadyFreshwater is less dense — 33ft seawater equals 34ft freshwater at the same pressure. Different ATA, different ppO₂, different EAD, slightly different tissue loading. DiveCommand corrects all of it automatically. Verified across all 11 test depths.
✓ SW / FW Density CorrectedYour Instructor.
Always Available.
DiveCommand includes an interactive AI dive planning assistant — tap the instructor button in the bottom corner of the planner and ask it anything. Why is my NDL shorter at altitude? What does 90% nitrogen load mean? How do gradient factors affect my ascent?
The assistant is trained on DiveCommand’s exact specs — Bühlmann ZHL-16C, the Δ=0 verification, GF 40/85 defaults, altitude corrections, and how every calculation works. It answers in plain language, like a knowledgeable instructor talking through a concept — not a manual entry.
Built on Claude by Anthropic. Your dive plans never leave the device. The assistant only needs internet to answer questions — not to run the planner.
“Why is my NDL shorter at altitude?” · “What does N₂ load 90% mean?” · “How do GF Lo and GF Hi change my plan?” · “What’s the difference between ppO₂ and CNS%?” · “Why does my Shearwater show a different NDL?”
Validated by an Independent Reference Implementation
DiveCommand’s ZHL-16C engine was validated using a Python reference implementation written entirely from scratch — separate codebase, same Bühlmann 1990 constants, no shared code with the JavaScript engine. Both were tested across 12,067 cases spanning every depth, gas mix, and GF combination. Agreement at Δ=0 at every single case. The harness is a self-contained HTML file — open it in any browser and run all 12,067 tests yourself.
What You Get When the Algorithm Is Exact
Most online dive planners use simplified formulas rather than the full Bühlmann model. Here’s the difference in practice.
| Capability | DiveCommand $49/yr or $149 lifetime |
Generic Planners Free / Various |
|---|---|---|
| Full Bühlmann ZHL-16C — not an approximation | ✓ | Approximate |
| GF 40/85 factory default — matches wrist computers | ✓ | — |
| Δ=0 verified vs Shearwater · Garmin · Suunto | ✓ | — |
| All 16 tissue compartments tracked simultaneously | ✓ | Rarely |
| Custom GF Low / GF High adjustment | ✓ | Sometimes |
| Trimix to 330ft · EAD · END · ENP · Z-factor | ✓ | Rarely |
| Rock bottom gas calculator | ✓ | — |
| 3-bottle stage/deco gas management | ✓ | — |
| Altitude corrections — sea level to 11,000ft | ✓ | Rarely |
| Freshwater / saltwater density toggle | ✓ | — |
| ppO₂ · MOD · CNS O₂ live tracking | ✓ | Some |
| SVG dive profile visualization | ✓ | Some |
| Integrated logbook · SAC rate · plan vs actual | ✓ | Some |
| Multi-day nitrogen carry-over | ✓ | — |
| CSV export for all logged dives | ✓ | Rarely |
| 100% offline · any device · no download | ✓ | Varies |
| Public validation harness (open-source test) | ✓ | — |
| Interactive AI planning assistant | ✓ | — |
| Lifetime license — no subscription | ✓ | Freemium |
Runs Offline. Works Anywhere.
Remote dive boat. Mountain lake. Liveaboard mid-ocean. DiveCommand installs once and runs completely offline — iOS, Android, Mac, Windows, tablet, or phone. Every tissue calculation, altitude correction, logbook entry, and printed plan works without a connection. A world-class decompression model that fits in your pocket and doesn’t need the internet to think. (The AI assistant is the only feature that requires internet — and only when you ask a question.)
Own Your Software. Own Your Profile.
Buy it once, use it forever. No subscription, no version upgrades to purchase, no recurring charges when your credit card expires.
- ✓Full Bühlmann ZHL-16C engine — GF 40/85 factory default, not an approximation
- ✓Δ=0 verified against Shearwater, Garmin, and Suunto at factory GF settings
- ✓16-compartment tissue tracking — live recalculation on every input change
- ✓Custom GF Low / GF High gradient factor adjustment
- ✓Technical mode: trimix to 330ft, EAD, END, ENP, Z-factor real gas
- ✓3-bottle stage/deco gas management + rock bottom gas calculator
- ✓ppO₂ · MOD · CNS O₂ tracking with live safety thresholds
- ✓Altitude corrections — sea level to 11,000ft with common elevation presets
- ✓Freshwater / saltwater density toggle — physics-corrected
- ✓SVG dive profile visualization · print-ready dive plans
- ✓Integrated logbook — site, buddy, SAC rate, plan vs actual
- ✓Multi-day expedition nitrogen carry-over
- ✓CSV export · 100% offline · any device · no account required
- ✓Interactive AI dive planning assistant — included, no extra charge
- ✓All future updates included — no version upgrades to purchase
Written by a Diver, Not a Developer Who Read About It
Scott Fontecchio is a PADI Master Scuba Diver Trainer and SSI Master Instructor with 40+ years of diving experience and 1,000+ dives. He built DiveCommand because he was tired of explaining to students why the planning software said one thing and their Shearwater said another — and tired of planning tools that required a desktop install and 20 minutes to produce a number he could have gotten in 30 seconds.
The Δ=0 verification isn’t a marketing claim — it’s the result of building a separate Python implementation from the same Bühlmann 1990 source, running 12,067 test cases, and confirming zero deviation at every single one. The math is the same because the same math was used.
The validation harness is public. Load it in a browser and run all the tests yourself. Then plan your last dive in DiveCommand and check the NDLs against your computer. That’s the whole pitch.
Need Commercial or Public Safety Dive Planning?
DiveCommand is built for recreational and technical divers. The DepthPlanner suite also includes two professional-grade planners for different missions.
Full U.S. Navy Rev 7 tables, ADCI/OSHA auto-generated commercial dive plans, N₂ diver status strip for full crew management. Fleet license available.
NIMS/ICS incident command for dive operations. Rescue vs Recovery Mode, OSHA staffing enforcement, chain of custody, contaminated water ops, one-tap incident report.
Two Minutes.
Any Device. Every Dive.
Open a browser, pick a depth and gas, get your NDL. No install, no account, no friction. When the numbers match your Shearwater, you’ll understand why this is the planner you’ll actually use.
✓ Any Device · Works Offline · No Account ✓ Δ=0 vs Shearwater · Garmin · Suunto