I'm trying to find the equation to calculate the height of volume in my kettle. I'm trying to figure out what size wort chiller will work. I know how to calculate the total volume of a kettle, just don't know how to calculate the height of the liquid in the kettle. For example, if I put 1 gallon of water in a 3 gallon kettle, the water height is 2.94 inches. I don't want to keep running to my computer to use the calculator, which won't show the equation. And I don't want to keep multiplying the number of gallons I pour in a kettle by 2.94 inches, because I know that's 1 gallon, but that will change depending on the size of the kettle.