Nitrox Calculator
MOD, EAD, ppO₂ — Instant calculations for your Nitrox dives
Interactive toolNitroxEANxHypoxic
⚠️ Warning — This tool is for informational purposes only. It does not replace Nitrox training or analysing your mix before every dive. Always verify your tank with an oxygen analyser. Formulas based on Dalton's law. Binary mixes only (O₂/N₂) — for trimix blends (with helium), the EAD and N₂ gain values do not apply.
Parameters
ppO₂
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ppN₂
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MOD
—
EAD
—
N₂ Gain
—
Status
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How to use
Enter the oxygen fraction of your mix (e.g., 32 for EAN32, 18 for a hypoxic mix), the planned depth, and your maximum ppO₂ limit (1.4 bar recommended, 1.6 bar maximum).
Results explained
- ppO₂ — Oxygen partial pressure at given depth. Above 1.6 bar: seizure risk (Paul Bert effect). Below 0.18 bar: hypoxia risk
- ppN₂ — Nitrogen partial pressure. Lower = less nitrogen loading
- MOD — Maximum Operating Depth where ppO₂ reaches your limit
- EAD — Equivalent Air Depth giving same nitrogen loading. Use this value in MN90 tables
- N₂ Gain — Nitrogen reduction compared to air (negative for hypoxic mixes)
Common mixes
| Mix | %O₂ | MOD (1.4) | MOD (1.6) | Typical use |
|---|---|---|---|---|
| Air | 21% | 56m | 66m | Standard |
| EAN28 | 28% | 40m | 47m | Deep recreational Nitrox |
| EAN32 | 32% | 33m | 40m | Standard recreational Nitrox |
| EAN36 | 36% | 28m | 34m | Shallow diving |
| EAN40 | 40% | 25m | 30m | Decompression gas |
| EAN50 | 50% | 18m | 22m | Deep stop |
| O₂ pure | 100% | 4m | 6m | 6m deco stop (MT2019) |
FAQ — Nitrox
Does Nitrox let you dive deeper?
No, the opposite. Nitrox REDUCES maximum depth (lower MOD than air) due to O₂ toxicity risk. Its advantage is reducing nitrogen loading, allowing longer dives or shorter stops at moderate depths.
Do I need special training for Nitrox?
Yes. In FFESSM, Nitrox qualification is available from N2. It covers theory (ppO₂, MOD, EAD calculations), practice (mix analysis, cylinder labeling), and specific safety procedures.
1.4 or 1.6 bar: which limit?
1.4 bar is recommended for the active phase (bottom time). 1.6 bar is the absolute limit, acceptable only for decompression stops with minimal physical activity. When in doubt, use 1.4 bar.
What is a hypoxic mix?
A mix is called hypoxic when its oxygen fraction is below 21% (air). Used in technical diving to reduce O₂ toxicity at great depths (beyond 50m), it becomes unbreathable at the surface: the minimum operating depth is calculated to maintain ppO₂ ≥ 0.18 bar. Specific tek training is mandatory.