Nitrox MOD Calculator

Updated November 2026 · free, works in your browser

The maximum operating depth (MOD) of a nitrox mix is the deepest point at which the oxygen partial pressure (PO2) stays within your chosen limit. For EAN32 with a 1.4 bar limit, the MOD is about 33 metres (110 feet). Enter your oxygen percentage above and pick 1.4 or 1.6 to see your own figure.

How to use the nitrox MOD calculator

1. Type the oxygen percentage you measured when you analysed your cylinder, for example 32 for EAN32.
2. Choose your maximum PO2: 1.4 bar is the usual limit for recreational diving, 1.6 bar is sometimes used for decompression gases.
3. Read the maximum operating depth in metres and feet.
4. Optionally enter a planned depth, in metres or feet, to see the PO2 you would breathe there and whether it stays inside your limit.
5. Use the copy button to share or save the result as a link.

How it is calculated

The calculation uses the standard formula taught in nitrox courses:

MOD (m) = 10 × (PO2max ÷ FO2 − 1)

• PO2max is the highest oxygen partial pressure you accept, in bar.
• FO2 is the oxygen fraction of the mix, so 32% is 0.32.
• The factor 10 reflects that in seawater each 10 metres of depth adds roughly 1 bar of pressure, and the "−1" removes the 1 bar of atmosphere at the surface.

Feet are found by dividing metres by 0.3048. Results are rounded down to a whole number, so the figure is never deeper than the exact value. The planned-depth check uses PO2 = (depth ÷ 10 + 1) × FO2.

MOD for common mixes

Values are rounded down to whole metres. This tool is a planning aid and does not replace nitrox training, gas analysis before every dive, or your dive computer settings.

Frequently asked questions

What is the MOD for nitrox 32?

At a PO2 limit of 1.4 bar, EAN32 has a MOD of 33.75 m, which is usually stated as 33 m (about 110 ft). At 1.6 bar it is 40 m (about 131 ft).

Should I use 1.4 or 1.6 bar?

Recreational nitrox training generally uses 1.4 bar as the working limit for the bottom part of a dive, with 1.6 bar seen as a contingency ceiling. Follow the limit taught by your training agency and set on your computer.

Does a higher oxygen percentage make me go deeper?

No, the opposite. More oxygen means the PO2 limit is reached at a shallower depth, so the MOD gets smaller. The benefit of nitrox is longer no-decompression time at moderate depths, not extra depth.

Is the MOD different in fresh water?

Fresh water is slightly less dense, so pressure increases a little more slowly with depth. The seawater formula used here is the common convention and errs slightly on the cautious side for fresh water.

Why does my cylinder analysis matter?

The MOD depends on the real oxygen content. A mix that analyses a percent or two higher than labelled has a shallower MOD, so always analyse and enter the measured value.

Planning dives away from home

Nitrox availability, cylinder fills and boat schedules vary between dive destinations, so it helps to know your numbers before you travel. Once you know which mixes and depths suit your plans, you can choose accommodation close to the harbour or dive centre, which makes early departures and gear handling much easier.