MOD meters-
MOD feet-
Ambient pressure-
Selected PPO2-
Enriched Air Planning
Nitrox Calculator: MOD, Best Mix, PPO2 & EAD
Calculate the most common recreational nitrox values in one place. Enter the analyzed oxygen percentage, depth or maximum oxygen partial pressure and the calculator does the standard gas-law math.
Calculator 1
Maximum Operating Depth (MOD)
MOD is the depth where your selected oxygen fraction reaches the selected maximum PPO2.
Calculator 2
Nitrox Best Mix Calculator
Best Mix calculates the oxygen fraction that reaches your selected PPO2 at the planned maximum depth.
Best Mix-
Exact oxygen-
Pressure at depth-
Result note-
Calculator 3
PPO2 at Depth Calculator
Partial pressure is the oxygen fraction multiplied by the absolute ambient pressure at depth.
PPO2-
Ambient pressure-
MOD at 1.4 ATA-
PPO2 note-
Calculator 4
Equivalent Air Depth (EAD)
EAD compares the nitrogen partial pressure of a nitrox dive with the depth that would produce the same nitrogen exposure on air.
EAD meters-
EAD feet-
Nitrogen fraction-
Oxygen at depth-
How the Math Works
Nitrox formulas used by this calculator
Depth to pressure: metric ATA = (depth in meters / 10) + 1. Imperial ATA = (depth in feet / 33) + 1.
PPO2: PPO2 = ATA x FO2, where FO2 is the oxygen fraction written as a decimal.
MOD: metric MOD = ((maximum PPO2 / FO2) - 1) x 10. Imperial MOD uses 33 instead of 10.
Best Mix: FO2 = maximum PPO2 / ATA at the planned maximum depth.
EAD: metric EAD = ((FN2 / 0.79) x (depth + 10)) - 10, where FN2 = 1 - FO2. Imperial uses 33 instead of 10.
Safety
A calculated number is not permission to make the dive
Analyze every nitrox cylinder, label it correctly and set your dive computer to the gas you are actually breathing. A 1.4 ATA PPO2 is commonly used as a recreational working limit; selecting a different value must be consistent with your training and dive procedure. This calculator does not calculate CNS oxygen exposure, decompression obligations or whether a dive is appropriate for your certification and experience.