The main formula for Nitrox calculations is based on Dalton's Law, which relates the partial pressure of oxygen (pO2)to the total pressure (P) and the fraction of oxygen (FO2): pO2 = FO2 X P. To find the maximum operating depth (MOD), you can rearrange the formula to P =pO2/FO2 and then subtract 1 bar for surface pressure and multiply by 10 to convert to meters. To find the "best mix" for a specific depth, you can use FO2 = pO2/((Depth/10)+1). But there is an easier way to remember this for calculating either Nitrox % or Maximum Operating Depth.

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Exceeding maximum operating depths can result in serious injuries.