Nitrox Calculators

Diving with Nitrox (Enriched Air Nitrox or EANx) can significantly extend your bottom time by reducing your nitrogen absorption, increasing your NDL or No Decompression Limit.

When diving with Nitrox, you need to keep in mind a few factors such as your PPo2, Max Operating Depth (MOD), and with those you often want to find the "best mix" for the depth you'll be diving to. By "best mix" we just mean the highest percentage of oxygen in your Nitrox blend that you can have at depth without exceeding a desired PPo2. For recreational diving, we recommend never exceeding a PPo2 of 1.4 to avoid risks of CNS and Oxygen Toxicity.

Feel free to share this calculator with your friends and bookmark it to use on future dive trips, but please take note of the Disclaimer at the bottom of this page. This does NOT replace Nitrox certification and you should still use a proper dive computer and/or dive tables to confirm.


For a more detailed guide to the formulas used in this calculator, watch our video on calculating max operating depth for Nitrox below.

Nitrox Diving Calculator

Nitrox Gas Formulas

Max Operating Depth (MOD)

Formula for calculating Pressure
PO2 / FO2 = P
Single Formula to Calculate in "One Formula"
((PPO2 / FO2) - 1 ) x 33 = MOD (for feet)
((PPO2 / FO2) - 1 ) x 10 = MOD (for meters)

Partial Pressure of Oxygen at Depth

FO2 X P = PPO2

"Best Mix" of Nitrox for a Depth

PO2 / P = FO2 ("Best Mix")

Convert Pressure to Depth (P to D)

(P - 1) x 33 = Depth in Feet
(P - 1) x 10 = Depth in Meters

Convert Depth to Pressure (D to P)

(D / 33) + 1 = Pressure (From feet)
(D / 10) + 1 = Pressure (From meters)
Disclaimer: This calculator is intended for educational purposes only and should not be used as a replacement for proper nitrox certification from an instructor who is active and certified through a recognized agency. The values provided by this calculator may not be 100% accurate and should not be relied upon for making any diving-delated decision. Always consult with a certified diving professional and use appropriate dive tables and dive computers when planning your dives. The use of this calculator is at your own risk. Thomas Hughes and CircleHScuba LLC assume no liability for any injuries, damages, or losses that may result from the use of this tool.
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