Nitrox MOD & EAD Calculator

Frequently Asked Questions

What is MOD (Maximum Operating Depth) in nitrox diving?

MOD is the deepest depth you can dive a given nitrox mix without exceeding your chosen oxygen partial pressure (ppO₂) limit. It's calculated as MOD = (ppO₂ / FO₂ − 1) × 10, where FO₂ is the fraction of oxygen in the mix (e.g. 0.32 for EAN32). Go deeper than your MOD and ppO₂ rises past safe limits, increasing the risk of oxygen toxicity.

What is EAD (Equivalent Air Depth)?

EAD tells you which depth on a standard air dive table has the same nitrogen loading as your nitrox dive at your actual depth. Because nitrox has less nitrogen than air, your EAD is always shallower than your real depth — this is what lets you use air dive tables (or get longer no-deco limits) while diving nitrox.

What ppO₂ limit should I use — 1.4 or 1.6?

1.4 bar is the standard recreational ceiling recommended by PADI, TDI and most training agencies for the working part of a dive. 1.6 bar is only used as a contingency/deco-stop limit for divers with Tec/deco certification — it is not a target for normal bottom time. When in doubt, plan and dive to the 1.4 limit.

How do I calculate MOD for a nitrox mix?

Pick your oxygen percentage and your ppO₂ limit (1.4 for recreational, 1.6 for deco contingency), then apply MOD = (ppO₂ / FO₂ − 1) × 10 in metres. For example, EAN32 (32% O₂) at ppO₂ 1.4 gives a MOD of about 33m. The calculator above does this instantly for any mix and depth.

Do I need certification to dive nitrox?

Yes — an Enriched Air / EANx certification (PADI, SSI, TDI and others all offer one) is required before diving nitrox, and it's typically a short course. Certification covers oxygen toxicity risk, MOD planning, analyzing your own tank before every dive, and equipment oxygen-cleaning requirements.