Maximum Operating Depth (MOD) and Scuba Diving

A maximum operating depth (MOD) is a depth limit based on the percentage of oxygen in a diver's breathing gas.

A diver should calculate the MOD for his dive whenever he uses enriched air nitrox, trimix, or pure oxygen. Technical divers who engage in deep air diving must also calculate MODs. 

A scuba diver who breathes air and who remains within recreational dive limits need not calculate a MOD for his dive. 

In fact, on most recreational dives the maximum depth will be limited by factors such as the no-decompression limit, narcosis, and the experience level of the diver instead of the MOD.



MOD Table (metric)

The table below shows the maximum operating depth (MOD) in meters at typical values for the partial pressure of oxygen (ppO2) in a bar with various percentages of oxygen (O2%).

Note that 21% is the normal air. The O2% values more commonly used in technical diving are highlighted.

All MOD values are rounded shallower.


Maximum Operating Depth (meters)
FO2 / O2%Maximum ppO2 (bar)
1.61.51.41.31.2
0.1 / 10%150.0140.0129.9119.9109.9
0.11 / 11%135.4126.3117.2108.199.0
0.12 / 12%123.3115.0106.698.389.9
0.13 / 13%113.0105.397.689.982.3
0.14 / 14%104.297.189.982.875.7
0.15 / 15%96.690.083.376.669.9
0.16 / 16%90.083.777.571.264.9
0.17 / 17%84.178.272.366.460.5
0.18 / 18%78.873.367.762.256.6
0.19 / 19%74.268.963.658.453.1
0.2 / 20%70.065.059.954.949.9
0.21 / 21%66.161.456.651.947.1
0.22 / 22%62.758.153.649.044.5
0.23 / 23%59.555.250.846.542.1
0.24 / 24%56.652.548.344.139.9
0.25 / 25%54.050.046.041.937.9
0.26 / 26%51.547.643.839.936.1
0.27 / 27%49.245.541.838.134.4
0.28 / 28%47.143.539.936.432.8
0.29 / 29%45.141.738.234.831.3
0.3 / 30%43.340.036.633.329.9
0.31 / 31%41.638.335.131.928.7
0.32 / 32%40.036.833.730.627.4
0.33 / 33%38.435.432.429.326.3
0.34 / 34%37.034.131.128.225.2
0.35 / 35%35.732.830.027.124.2
0.36 / 36%34.431.628.826.123.3
0.37 / 37%33.230.527.825.122.4
0.38 / 38%32.129.426.824.221.5
0.39 / 39%31.028.425.823.320.7
0.4 / 40%30.027.524.922.419.9
0.41 / 41%29.026.524.121.719.2
0.42 / 42%28.025.723.320.918.5
0.43 / 43%27.224.822.520.217.9
0.44 / 44%26.324.021.819.517.2
0.45 / 45%25.523.321.118.816.6
0.46 / 46%24.722.620.418.216.0
0.47 / 47%24.021.919.717.615.5
0.48 / 48%23.321.219.117.014.9
0.49 / 49%22.620.618.516.514.4
0.5 / 50%22.020.018.015.913.9
0.51 / 51%21.319.417.415.413.5
0.52 / 52%20.718.816.914.913.0
0.53 / 53%20.118.316.414.512.6
0.54 / 54%19.617.715.914.012.2
0.55 / 55%19.017.215.413.611.8
0.56 / 56%18.516.714.913.211.4
0.57 / 57%18.016.314.512.811.0
0.58 / 58%17.515.814.112.410.6
0.59 / 59%17.115.413.712.010.3
0.6 / 60%16.615.013.311.69.9
0.61 / 61%16.214.512.911.39.6
0.62 / 62%15.814.112.510.99.3
0.63 / 63%15.313.812.210.69.0
0.64 / 64%15.013.411.810.38.7
0.65 / 65%14.613.011.59.98.4
0.66 / 66%14.212.711.29.68.1
0.67 / 67%13.812.310.89.47.9
0.68 / 68%13.512.010.59.17.6
0.69 / 69%13.111.710.28.87.3
0.7 / 70%12.811.410.08.57.1
0.71 / 71%12.511.19.78.36.9
0.72 / 72%12.210.89.48.06.6
0.73 / 73%11.910.59.17.86.4
0.74 / 74%11.610.28.97.56.2
0.75 / 75%11.310.08.67.35.9
0.76 / 76%11.09.78.47.15.7
0.77 / 77%10.79.48.16.85.5
0.78 / 78%10.59.27.96.65.3
0.79 / 79%10.28.97.76.45.1
0.8 / 80%10.08.77.46.24.9
0.81 / 81%9.78.57.26.04.8
0.82 / 82%9.58.27.05.84.6
0.83 / 83%9.28.06.85.64.4
0.84 / 84%9.07.86.65.44.2
0.85 / 85%8.87.66.45.24.1
0.86 / 86%8.67.46.25.13.9
0.87 / 87%8.37.26.04.93.7
0.88 / 88%8.17.05.94.73.6
0.89 / 89%7.96.85.74.63.4
0.9 / 90%7.76.65.54.43.3
0.91 / 91%7.56.45.34.23.1
0.92 / 92%7.36.35.24.13.0
0.93 / 93%7.26.15.03.92.9
0.94 / 94%7.05.94.83.82.7
0.95 / 95%6.85.74.73.62.6
0.96 / 96%6.65.64.53.52.4
0.97 / 97%6.45.44.43.42.3
0.98 / 98%6.35.34.23.22.2
0.99 / 99%6.15.14.13.12.1
1 / 100% 6.05.03.92.91.9


This table provides information about gas use in scuba diving. 

UNDER NO CIRCUMSTANCES is there any implication that any gas mixture is safe or even life-supporting at any depth? 

If you have not received training in technical scuba diving, Nitrox, Trimix, or Heliox you should not attempt to use any of these results. 

Improper use of gasses in diving can result in injury or DEATH.

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