Shows how a volume of gas changes between two depths. Pressure times volume stays the same, as long as you work in absolute pressure.
The formula: P1 x V1 = P2 x V2 (absolute). Change any box and the full working updates. For study only, never for dive planning.
The IMCA ADS, BDS and LST papers ask this as a four-option question, with a calculator on screen. A free account gives you 15 practice questions for each exam, each with the worked answer and the document it comes from.