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Nitrox Tools

Quick-reference calculators for MOD, best mix, equivalent air depth, and ppO2 — for any nitrox blend. All math runs locally in your browser.

Units:
Max ppO2: Common ppO2s: (used for MOD & Best Mix)

Maximum Operating Depth (MOD)

The deepest you can safely breathe a mix before ppO2 exceeds the limit above.

%
MOD —ft

Formula MOD = ((ppO2 max / FO2) − 1) × 33

Best Mix for Target Depth

The highest-O2 mix that stays within the ppO2 limit at your planned depth.

ft
ft

Add a depth buffer beyond the Maximum planned bottom depth so your mix stays within the ppO2 limit even if you accidentally go deeper. Best mix will be calculated based on Maximum planned bottom depth + Depth Buffer.

Best mix FO2 —%

Formula FO2 = ppO2 max / (((max planned depth + buffer) / 33) + 1)

Equivalent Air Depth (EAD)

The depth a given nitrox mix behaves like for no-deco / tissue-loading calculations on air tables.

%
ft
EAD —ft

Formula EAD = (((1 − FO2) / 0.79) × (depth + 33)) − 33

Equivalent Narcotic Depth (END)

For trimix divers: the air-equivalent depth that produces the same narcotic load as your mix at the given depth.

%
%
— %
ft
END —ft

Formula

ppO2 at Depth

The oxygen partial pressure your lungs see at a given depth breathing a given mix.

%
ft
ppO2 —bar

Formula ppO2 = FO2 × ((depth / 33) + 1)

Common Mixes — MOD at current ppO2

Safety reminder: These calculators are for planning and reference only. Always analyze your mix on the tank before diving, respect your agency's and personal ppO2 limits, and follow your training. No online tool replaces proper dive planning.