If you have the depth and width of each seam, along with linear feet, that will give you a volume. The manufacturer or their rep could help you figure it from there. Often on a tube of caulking it will state how many linear feet of a certain size bead (example 3/8" bead) it will do--I've always assumed a square bead and multiplied from that. I do tend to purchase too much caulking material. In the USA, a San Diego company called Sunshine Supply LINK www.sunshinesupply.com/
was where I purchased my stuff and they were helpful with quantities as well.