Nitrox MOD table
The maximum operating depth (MOD) of every nitrox mix from air (21% oxygen) to EAN40, at the three common PPO₂ limits, in salt water. Each cell shows the plan max in bold, which is the MOD rounded down to a whole metre or foot, with the exact MOD beneath it. Plan your dive no deeper than the plan max.
MOD in metres, salt water
| Mix | PPO₂ 1.2Conservative | PPO₂ 1.4Standard | PPO₂ 1.6Contingency |
|---|---|---|---|
| Air (21%) | 47 mMOD 47.1 | 56 mMOD 56.6 | 66 mMOD 66.1 |
| EAN22 | 44 mMOD 44.5 | 53 mMOD 53.6 | 62 mMOD 62.7 |
| EAN23 | 42 mMOD 42.1 | 50 mMOD 50.8 | 59 mMOD 59.5 |
| EAN24 | 40 mMOD 40.0 | 48 mMOD 48.3 | 56 mMOD 56.6 |
| EAN25 | 38 mMOD 38.0 | 46 mMOD 46.0 | 54 mMOD 54.0 |
| EAN26 | 36 mMOD 36.1 | 43 mMOD 43.8 | 51 mMOD 51.5 |
| EAN27 | 34 mMOD 34.4 | 41 mMOD 41.8 | 49 mMOD 49.2 |
| EAN28 | 32 mMOD 32.8 | 40 mMOD 40.0 | 47 mMOD 47.1 |
| EAN29 | 31 mMOD 31.3 | 38 mMOD 38.2 | 45 mMOD 45.1 |
| EAN30 | 30 mMOD 30.0 | 36 mMOD 36.6 | 43 mMOD 43.3 |
| EAN31 | 28 mMOD 28.7 | 35 mMOD 35.1 | 41 mMOD 41.6 |
| EAN32 | 27 mMOD 27.5 | 33 mMOD 33.7 | 40 mMOD 40.0 |
| EAN33 | 26 mMOD 26.3 | 32 mMOD 32.4 | 38 mMOD 38.4 |
| EAN34 | 25 mMOD 25.2 | 31 mMOD 31.1 | 37 mMOD 37.0 |
| EAN35 | 24 mMOD 24.2 | 30 mMOD 30.0 | 35 mMOD 35.7 |
| EAN36 | 23 mMOD 23.3 | 28 mMOD 28.8 | 34 mMOD 34.4 |
| EAN37 | 22 mMOD 22.4 | 27 mMOD 27.8 | 33 mMOD 33.2 |
| EAN38 | 21 mMOD 21.5 | 26 mMOD 26.8 | 32 mMOD 32.1 |
| EAN39 | 20 mMOD 20.7 | 25 mMOD 25.8 | 31 mMOD 31.0 |
| EAN40 | 20 mMOD 20.0 | 25 mMOD 25.0 | 30 mMOD 30.0 |
MOD in feet, salt water
| Mix | PPO₂ 1.2Conservative | PPO₂ 1.4Standard | PPO₂ 1.6Contingency |
|---|---|---|---|
| Air (21%) | 155 ftMOD 155.5 | 187 ftMOD 187.0 | 218 ftMOD 218.4 |
| EAN22 | 147 ftMOD 147.0 | 177 ftMOD 177.0 | 207 ftMOD 207.0 |
| EAN23 | 139 ftMOD 139.1 | 167 ftMOD 167.8 | 196 ftMOD 196.5 |
| EAN24 | 132 ftMOD 132.0 | 159 ftMOD 159.5 | 187 ftMOD 187.0 |
| EAN25 | 125 ftMOD 125.4 | 151 ftMOD 151.8 | 178 ftMOD 178.2 |
| EAN26 | 119 ftMOD 119.3 | 144 ftMOD 144.6 | 170 ftMOD 170.0 |
| EAN27 | 113 ftMOD 113.6 | 138 ftMOD 138.1 | 162 ftMOD 162.5 |
| EAN28 | 108 ftMOD 108.4 | 132 ftMOD 132.0 | 155 ftMOD 155.5 |
| EAN29 | 103 ftMOD 103.5 | 126 ftMOD 126.3 | 149 ftMOD 149.0 |
| EAN30 | 99 ftMOD 99.0 | 121 ftMOD 121.0 | 143 ftMOD 143.0 |
| EAN31 | 94 ftMOD 94.7 | 116 ftMOD 116.0 | 137 ftMOD 137.3 |
| EAN32 | 90 ftMOD 90.7 | 111 ftMOD 111.3 | 132 ftMOD 132.0 |
| EAN33 | 87 ftMOD 87.0 | 107 ftMOD 107.0 | 127 ftMOD 127.0 |
| EAN34 | 83 ftMOD 83.4 | 102 ftMOD 102.8 | 122 ftMOD 122.2 |
| EAN35 | 80 ftMOD 80.1 | 99 ftMOD 99.0 | 117 ftMOD 117.8 |
| EAN36 | 77 ftMOD 77.0 | 95 ftMOD 95.3 | 113 ftMOD 113.6 |
| EAN37 | 74 ftMOD 74.0 | 91 ftMOD 91.8 | 109 ftMOD 109.7 |
| EAN38 | 71 ftMOD 71.2 | 88 ftMOD 88.5 | 105 ftMOD 105.9 |
| EAN39 | 68 ftMOD 68.5 | 85 ftMOD 85.4 | 102 ftMOD 102.3 |
| EAN40 | 66 ftMOD 66.0 | 82 ftMOD 82.5 | 99 ftMOD 99.0 |
The three PPO₂ limits
1.2Conservative. Shallower limit with a larger oxygen-toxicity margin — long, repetitive or cold dives, and technical practice.
1.4Standard. The recreational working limit taught by every major training agency. Recommended for normal dives.
1.6Contingency. A deeper ceiling for emergencies or decompression stops only, with appropriate training — never a planning target.
How MOD is calculated
MOD (m) = dpa × ( PPO₂ / FO₂ − 1 )
dpa = 10 m / 33 ft · fresh 10.3 m / 34 ft
dpa = 10 m / 33 ft · fresh 10.3 m / 34 ft
FO₂ is the oxygen fraction: 32% is written as 0.32. In fresh water every MOD is slightly deeper (about 1 m on a 33 m MOD). Salt water is the conservative default and is safe to apply in fresh water.
This app provides simple nitrox gas calculations. It is not a dive computer, decompression planner, or substitute for certified scuba training. Always analyze your gas, label your cylinder, set your dive computer, and follow your training, local rules, and dive plan.