Nitrox Basics: EAN32 vs EAN36

EAN32 and EAN36 are the two most commonly available nitrox mixes at dive shops worldwide. But which one should you use? The answer depends on where you are going and what you want to get out of the dive.

What EAN32 and EAN36 mean

The naming convention is simple: EAN stands for “Enriched Air Nitrox” and the number is the oxygen percentage.

• EAN32 (Nitrox 32): 32% oxygen, 68% nitrogen
• EAN36 (Nitrox 36): 36% oxygen, 64% nitrogen
• For comparison, air is approximately 21% oxygen, 79% nitrogen

Both mixes have more oxygen and less nitrogen than air. More oxygen is not the benefit — less nitrogen is. Reducing the nitrogen fraction means less nitrogen dissolves into your tissues, which translates to longer no-decompression limits and reduced decompression sickness (DCS) risk.

Depth limits

Every nitrox blend has a Maximum Operating Depth determined by the oxygen fraction and your ppO2 limit:

At a ppO2 limit of 1.4 bar (the standard recreational limit):

• EAN32: Safe to 33 meters (110 feet)
• EAN36: Safe to 28 meters (95 feet)

This is the fundamental tradeoff: EAN36 gives you less nitrogen but also less depth range.

No-decompression time comparison

Here is where the practical benefit shows up. Approximate no-deco limits using common recreational tables:

At 18 meters, EAN32 nearly doubles your no-deco time compared to air. EAN36 more than doubles it. At 24 meters, EAN36 gives you roughly twice the air no-deco time. At 30 meters, only EAN32 is usable (EAN36 exceeds its MOD).

When to use each

Choose EAN32 when:

• Your dive will reach 30-33 meters
• You want a single mix that works across a wide depth range
• The dive shop does not offer custom blends
• You want to maximize flexibility for multi-level profiles

Choose EAN36 when:

• Your dive will stay above 28 meters
• You want maximum bottom time at moderate depths (18-27 meters)
• You are doing repetitive dives and want to minimize nitrogen loading across the day
• Your dive plan is focused on a reef or wall in the 15-25 meter range

Stick with air when:

• You are diving very shallow (under 15 meters), where the nitrogen reduction matters less
• Nitrox is not available
• Budget is a concern (nitrox fills often cost more than air)

Practical tips

• Always analyze your tank: Before every dive on nitrox, personally verify the oxygen content with an analyzer. Write the analysis, MOD, date, and your initials on the tank label
• Set your computer: Make sure your dive computer is set to the correct gas mix. Forgetting to switch from air to your actual nitrox blend means your computer will calculate more conservatively than necessary (not dangerous, but you lose the benefit)
• Same mix for buddy pairs: Ideally, both divers in a buddy pair should be on the same mix. This simplifies gas management and means you share the same depth limits
• Watch your MOD: The biggest risk with nitrox is going deeper than your MOD. Set a depth alarm on your computer at your MOD

Common misconceptions

“Nitrox lets you dive deeper.” No — it does the opposite. Nitrox gives you a shallower MOD than air because of the increased oxygen fraction. The benefit is longer bottom time and reduced nitrogen loading within the allowed depth range.

“Nitrox reduces air consumption.” No. You breathe the same volume of gas regardless of the mix. Your surface air consumption (SAC) rate does not change with nitrox. You gain time because of reduced nitrogen loading, not reduced gas usage.

“More oxygen is always better.” Not at depth. More oxygen means a shallower MOD and increased risk of oxygen toxicity if you exceed it. The right amount of oxygen is the amount that is safe at your planned depth — no more.

Sources

• PADI Enriched Air Diver Manual
• NOAA Diving Manual, 6th Edition
• DAN (Divers Alert Network) Enriched Air Diving Resources