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OTU

Oxygen Tolerance Units

Whole-body (pulmonary) oxygen exposure, for a dive or a run of diving days.

Metric shows depths in metres and pressures in bar; Imperial in feet and atm. Your choice is kept across every formula for this visit.
Recreational limits mixes to 21–40% oxygen (nitrox). Technical allows any oxygen percentage up to 100% and trimix (helium). Granular lets you type exact values, to a decimal place. Your choice is kept across every formula for this visit.
Fresh water is less dense than salt water, so the same pressure is reached a little deeper (10.3 m per bar, against 10 m in salt water).
Your gas, depth and time
The oxygen in your mix: 21% is air, 32% and 36% are common nitrox mixes. Recreational limits run up to 40%.
The deepest point of your planned dive. Recreational goes to 45 m (150 ft); deeper needs Technical.
How long you spend at this depth. One depth and one time: for a dive with several levels, this is a guide only.

I think this is an error

This sends the calculation on this screen, exactly as it is now.