Equivalent Air Depth (EAD) Calculator
See how deep a nitrox mix feels to your body in nitrogen terms. The equivalent air depth is the air depth with the same nitrogen partial pressure, which is what air dive tables are built around.
How to calculate equivalent air depth
- Enter the oxygen percentage of your nitrox mix, such as 32.
- Enter your planned depth in metres or feet.
- Read the equivalent air depth and use it with your air tables or computer.
Examples
EAN32 at 30 m
Oxygen 32%, depth 30 m
EAD 24.43 m
EAN32 at 100 ft
Oxygen 32%, depth 100 ft
EAD 81.48 ft
Frequently asked questions
What is equivalent air depth?
EAD is the depth at which ordinary air would give the same nitrogen partial pressure as your nitrox mix at the real depth. It lets you reuse air no-decompression tables for a nitrox dive.
What is the equivalent air depth formula?
With FN2 as one minus oxygen percent over 100, EAD in metres is (FN2 / 0.79) times (depth plus 10) minus 10. In feet it is (FN2 / 0.79) times (depth plus 33) minus 33.
Why is the equivalent air depth shallower than my real depth?
Nitrox holds less nitrogen than air, so at the same depth it loads less nitrogen. The equivalent air depth is therefore shallower, which is why nitrox stretches your no-decompression time.
Does a lower EAD reduce narcosis?
Nitrogen narcosis tracks nitrogen partial pressure, so a lower EAD does suggest less nitrogen narcosis than air at that depth. Oxygen can be narcotic too, so do not treat nitrox as narcosis free.
Can I rely on this instead of training?
No. This is a training and planning aid only. Get certified for nitrox, analyse your gas, follow your training and always defer to your dive computer and tables underwater.
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