What are the units of measure used in Kerbal Space Program?

Kerbal Space Program is, ostensibly, all about having fun with rocket science. Of course, much of rocket science is dependent upon mathematics. Sure, there's plenty of mods and tools to help you out with calculating delta-V, TWR, and the like. But sometimes you want to stretch out and go beyond what the tools are designed to do for you. Without having an actual, deep understanding of the physics and all behind these things, this leaves many of us Googling up equations and tossing numbers at them to see what they spit out.

However, certain equations are designed around specific units of measure so that their results are properly scaled to the forces expected to be in play. This presents a problem when we try to carry over details from Kerbal Space Program where the measurement units are not specified in-game. In order come up with correct (or even remotely accurate) answers to our questions, we need to know which units of measure are being used in-game and how they compare to real-world units.

Some of the most critical units that are unspecified in-game are seen in the Vehicle Assembly Building and Space Plane Hangar, where we're dealing with various properties of the parts that will make up whatever it is we're hoping to not have blow up in our face. (Or, for some of us, whatever we're hoping to make blow up in our face spectacularly!) There may be others used in these or other interfaces I'm not thinking of, but I'm particularly looking to at least get the following defined:

• Standard unit of mass used to measure parts and fuel.
• Units of mass and/or volume used to measure all fuel types.
• Liquid Fuel
• Oxidizer
• Solid Fuel
• Monopropellant
• Xenon Gas
• Intake Air
• Units used to describe applied forces.
• Thrust
• Torque

For each of the above (and any I've missed), I want to know:

• What is the unit of measure used for in-game displays?
• If the unit is unique to Kerbal Space Program, how can I convert it to a usable real-world unit? (Or is proper conversion impossible?)

(Note: This should probably be a Community Wiki)

1 Answer

Everything in Kerbal Space Program uses the Metric system

Distances are measured in (kilo)metres

Masses are measured in metric tons (this applies to both parts and fuels).

• Xenon Gas is measured as mass per unit not volume: 0.1 kg per unit
• All other gasses are 5kg per unit

Volumes (for all other liquid fuel, oxidizer, monopropellant, solid fuel etc), are measured as 2-2.5 litres per unit.

Thrust is measured in kilo-newtons.

No real world analogue exists for electric charge. It is speculated a unit of electric charge is, as estimated from the capacity batteries and the consumers, it is about 10 kJ (power of 10 kW for a second).

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