This should be simple, but I can't get it to work.  We purchase 10-5 gallon jugs of water.  But we break it down in kilograms when we use it for production.  The end result is sold in ounces.  I figured out 5 gallons =18.93 kilograms.  I have to order it and receive it from the vendor gallons. But that doesn't equate when we inventory it in Kilograms. And it throws the cost of materials off.  How can I fix this?