Oxygen Not Included – Ultimate Gas Weight Guide

In this guide I’ll go through all the different Gasses there are in the game right now and their relative “weight” in terms of what floats on what.

Other ONI Guides:

The Different Weights of Gasses

I’ve made a big neutronium box and put one tile of every material there is (except neutronium because that doesn’t ever change into a gas) in at 9000 Kelvin and a pressure of 1000 Kgs. This way I found what turns into what and how much it “weighs”. I also encountered lots of crashes and bugs when there are materials at a very high pressure and even got my game to go into a glitched state where it wouldn’t let any material change itself into another. (For example 9000 Kelvin hot water wouldn’t boil.) So here we go here are the Gasses from lightest to heaviest.


  • Hydrogen
  • Helium
  • Carbon
  • Oxygen
  • Polluted Oxygen
  • Natural Gas
  • Steam
  • Chlorine
  • Phosphorus
  • Carbon Dioxide
  • Rock Gas
  • Steel
  • Copper
  • Tungsten
  • Gold


Also here is a screenshot of the testsetup.

Oxygen Not Included - Ultimate Gas Weight Guide

It’s interesting to note that the most common gas that is produced by having materials evaporate is Rock Gas. Please note that the colors of the gases in this picture aren’t representative of how many different gasses there are. The muddy brown grey in the lower right corner are the all the different metals and they all have the same color. Although the big orange part is all Rock Gas. This is because many materials in this game are rocks, or they become something rock like and turn into Rock Gas once they reach a certain temperature.

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