Equivalent Air Depth - Calculations in Feet

Calculations in Feet

The equivalent air depth can be calculated for depths in feet as follows:

EAD = (Depth + 33) × Fraction of N₂ / 0.79 − 33

Working the earlier example, for a nitrox mix containing 64% nitrogen (EAN36) being used at 90 feet, the EAD is:

EAD = (90 + 33) × 0.64 / 0.79 − 33

EAD = 123 × 0.81 − 33

EAD = 100 − 33

EAD = 67 feet

So at 90 feet on this mix, the diver would calculate their decompression requirements as if on air at 67 feet.