Nitrox Calculator: MOD, EAD, Best Mix
Three calculators for Enriched Air Nitrox: Maximum Operating Depth (MOD), Equivalent Air Depth (EAD), and Best Mix for a target depth.
Do not exceed 33.8 m on EAN32 at PpO₂ 1.4.
O₂ toxicity caveat: MOD is hard-limit, not target. Above MOD → CNS oxygen toxicity → convulsions underwater (typically fatal). Even at PpO₂ 1.4, accumulate CNS% across the dive (use OTU/CNS tracker on dive computer for repetitive).
Disclaimer: This tool is an educational aid. It is not a substitute for a personal dive computer, proper certification, or current medical advice. Plan dives conservatively and consult a dive professional when in doubt. Emergency: DAN Asia-Pacific +61-8-8212-9242.
Frequently asked questions
Why is MOD limit lower than the typical depth I dive on air?
That's the trade-off. EAN32 at PpO2 1.4 = MOD 33m. EAN36 = 28m. Nitrox is for 18-30m dives where you want longer bottom time — not for going deeper than air would allow.
Can I use a computer's air-mode NDL with Nitrox?
Yes — that's exactly what EAD calculates. EAN32 at 22m = EAD 17.7m. You look up NDL for 18m air on your table. Some divers do this to extend dives even when their computer is in air mode (no Nitrox setting). Better: set your computer to Nitrox mode and let it track properly.
How do I verify a tank's Nitrox %?
Every Nitrox dive starts with an O2 analyser check — usually a Vandagraph or Maxtec analyser the dive shop provides. Check before signing the cylinder log. If shop says EAN32 but analyser shows 28%, refuse the tank (MOD shifts to 40m, but more importantly the shop's mixing isn't reliable).
What's the deal with PpO2 1.4 vs 1.6 vs 1.2?
1.4 bar PpO2 is the recreational working limit. 1.6 was historical and is sometimes allowed for shallow decompression stops only. 1.2 is conservative — for cold water, hard work, repetitive deep diving, or known O2-sensitive divers. Tech diving uses 1.4 working / 1.6 deco / 1.0 background.