Diving tool · Nitrox
Nitrox calculator: MOD and EAD
Enter the oxygen percentage of your tank to see how deep you can go with this mix (MOD). Add a depth to also get the oxygen partial pressure at that depth and the equivalent air depth (EAD). Results are always rounded to the safe side.
Maximum operating depth (MOD)
33 m
32% oxygen with a 1.4 bar limit. Exact result 33.75 m; rounded down to the safe side.
1.6 bar is a contingency limit; do not plan your dive to it.
Equivalent air depth (EAD)
Oxygen partial pressure at this depth
Requires nitrox certification. This calculation does not replace your training or your dive computer.
Before you calculate
- Analyse the mix yourself with an analyser before the dive and mark it on the tank. Enter the value you measured, not the one on the label.
- Diving with nitrox requires nitrox training and certification.
- Exceeding the MOD can cause oxygen toxicity and a convulsion underwater. Set your dive computer to the same mix; this page does not replace it.
- The calculation is for seawater (10 m = 1 bar). In fresh water the real limit is slightly deeper, so the result stays on the safe side. Lakes at altitude are outside the scope of this calculation.
MOD for common mixes
Values are calculated with the formula on this page and rounded down. Published tables often round to the nearest whole number, so some of our values are one metre shallower.
| Mix | MOD · 1.4 bar | MOD · 1.6 bar |
|---|---|---|
| Air (21%) | 56 m | 66 m |
| EAN28 (28%) | 40 m | 47 m |
| EAN30 (30%) | 36 m | 43 m |
| EAN32 (32%) | 33 m | 40 m |
| EAN34 (34%) | 31 m | 37 m |
| EAN36 (36%) | 28 m | 34 m |
| EAN40 (40%) | 25 m | 30 m |
The 1.6 bar column is a contingency limit only.
How the calculation works
These are the formulas in the US Navy Diving Manual and used by training agencies. FO₂ is the oxygen fraction, FN₂ the nitrogen fraction (1 − FO₂), D the depth in metres.
| Value | Formula (metres, seawater) | Rounding |
|---|---|---|
| MOD | 10 × (pO₂ ÷ FO₂ − 1) | Down (shallower) |
| EAD | (D + 10) × (FN₂ ÷ 0,79) − 10 | Up (more conservative) |
| pO₂ | FO₂ × (D ÷ 10 + 1) | Up (more conservative) |
The US Navy Diving Manual gives 1.4 bar as the normal working limit; at 1.6 bar the risk of central nervous system oxygen toxicity becomes significant.
Flying after diving
- A single no-decompression dive: at least 12 hours before flying.
- Several dives a day or several days of diving: at least 18 hours.
- Dives with decompression stops: substantially longer than 18 hours.
These are the recommendations from DAN’s 2002 workshop. DAN itself notes that they are based on trials with resting subjects, and that in 34% of flying-related decompression sickness cases the diver had waited more than 24 hours, so these times do not remove the risk. If your dive computer shows a longer time, follow it. If you have any symptoms of decompression sickness, do not fly and call emergency services (112).