How do you calculate kpa/min?? 1. I am trying to find the rate of CO2 production in yeast fermentation. I used a gas pressure sensor to measure the kpa every minute. I recorded the initial kpa and the kpa after every minute for four minutes. I forgot how to calculate the kpa/min and need clarification 2. I think the equation is something like this: Initial pressure - final pressure/ (seconds?) I doubt this is right 3. For instance, the initial pressure was 99.05 kpa and after a minute it was 99.03. So would the rate be -.02 kPa/min? Can someone please help or steer me in the right direction? Any help would be appreciated.