That is the way it functions, I observed it when I was doing my Mun refinery design tests. Your initial conversion was wrong, you were right to think the output you were getting was too high. The conversion is based on essentially two main factors "density" and "efficiency". The densities for liquid fuel and oxidizer is 5000 kg/m³, RCS fuel is 4000 kg/m³, and I have no idea about Xenon, I've never really used it (if anyone knows please feel free to share). The base equation you are looking for is (KethaneConsumption/density_of_fuel_in_tons)*efficiency=Units_ of_fuel, having said that there are small errors somewhere in the calculations, or possibly in one of my conversions that introduces a small error I have observed when refining large quantities of Kethane into various types of fuel. I was working on some different experiments to help me figure out where the error was when I had to abandon my game because if I land on anywhere my game wont let me do anything. With a large converter every second gets you: 13.5 kethane gets you a little under 2.7 liquid fuel 16.5 kethane gets you a little under 3.3 oxidizer 6 kethane gets you a little over 1 monopropellant I actually developed the same concept you did, however I think our implementation is different. It sounds like you want a base on the surface of something and you bring it there for refinement. What I did is I put a small space station in orbit and I began with a lander to drill the kethane (i developed a lander that was 2 parts, 1 had all the kethane equipment I needed and the other was for orbital redevious, when it refueled the space station it would go back down to the kethane section and dock), drill/convert/ferry/dock over and over, but once I started going out to other planets I realized I needed something that was able to produce in larger quantities, that's when I developed my refining rigs the down side is this is where i found out deposits could run out (enter the debugger, to replenish the kethane supply), and I built a cargo ship to ferry the fuel back and fourth with quantum fuel transfer mod. So I had a stationary tanker, that had wheels for positioning, and would drill kethane, another to store the fuel, and another to provide power and convert the fuel.