Turns feet of seawater into atmospheres absolute and psi: divide the depth by 33 and add 1.
The formula: ata = fsw/33 + 1; psia = ata x 14.7. 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.