Dive Planning Tool (Educational Estimate)
This calculator is for learning and rough planning only. It is not a substitute for a certified dive computer, formal training, or validated decompression software.
What this decompression dive calculator does
This tool estimates whether your planned dive remains within no-decompression limits (NDL) or requires staged decompression stops. It uses a practical recreational-style approach: depth and gas are converted into an equivalent air depth, then compared against a standard NDL table. If your bottom time exceeds that estimate, the calculator generates a conservative staged ascent profile.
In short, it helps you answer three useful questions quickly:
- Am I likely inside no-decompression limits?
- If not, how much staged stopping time might I need?
- What is my approximate total run time from descent to surfacing?
How decompression works (in plain language)
Inert gas uptake
When you descend, pressure increases and your body absorbs more inert gas (mostly nitrogen on air/nitrox). The deeper and longer you stay, the more gas is dissolved in tissues.
Controlled release during ascent
On ascent, pressure drops. If you ascend too quickly, dissolved gas can form bubbles, which raises decompression sickness risk. Stops give your body time to eliminate gas more gradually.
No-decompression vs decompression dives
A no-decompression dive means you can ascend directly (at a controlled rate) with a safety stop. A decompression dive means direct ascent is no longer acceptable; mandatory stops are required.
Calculation method used on this page
This page uses a simple educational model and not a full tissue-compartment decompression algorithm. The math is intentionally transparent:
- Equivalent Air Depth (EAD): adjusts nitrogen loading for nitrox mixes.
- Interpolated NDL: estimates no-decompression time from a depth-to-NDL table.
- Excess time: bottom time minus NDL (if positive).
- Staged stop estimate: distributes decompression minutes over 9 m, 6 m, and 3 m stops when required.
- Total runtime: bottom time + stop time + ascent transit time.
The output is deliberately conservative and instructional. For real dive execution, use your training agency procedures, dive computer, gas plan, and buddy/team protocol.
How to use this calculator effectively
1) Enter realistic dive parameters
Use your expected maximum depth, planned bottom time, and the oxygen percentage of your breathing gas. Set ascent rate to your standard practice (many divers use around 9 m/min).
2) Check oxygen depth limits
The calculator also computes an estimated MOD at PPO2 1.4 ata. If your planned depth exceeds MOD, treat that as a hard warning.
3) Review stop schedule and runtime
If no decompression is required, you should still include a safety stop when conditions allow. If decompression is indicated, the generated stops are an educational sketch only, not an execution-ready technical plan.
Best-practice reminders for safer diving
- Stay well within your training and certification limits.
- Use conservative settings on your dive computer.
- Ascend slowly and never skip required stops.
- Avoid heavy exertion during and after deep dives.
- Hydrate and plan generous surface intervals.
- When in doubt, shorten bottom time and add conservatism.
Important safety disclaimer
This decompression dive calculator is an educational aid only. It does not model full decompression physiology, repetitive dive history, personal risk factors, altitude, cold stress, workload, or equipment failures. Do not use this as your sole source for real-world dive decisions.