What are the real world measurements in Unity?

http://answers.unity3d.com/questions/17670/what-does-unity-measure-distance-in.html

Yes, it is meters and kilograms, end of story.

For sure - advanced users can make them "anything they want" (but then, you can do "anything at all you want" for that matter). The simple answer is m and kg.

Mass is 100% NOT kilograms. You may think that's "simple", but it's just plain wrong, sorry. Mass is just mass, with no relation to anything else. Distance measurements are meters by default due to some default settings in Unity, but that's not the case with mass. In fact saying that mass is kilograms is not a very good idea, since you will likely suffer from floating point precision issues if you try to use "real" weight in kg for larger objects. The fact is that an object with a mass of 1 colliding with an object with a mass of .5 behaves the same as an object with a mass of 1000 colliding with an object with a mass of 500. So you're usually better off just using 1 as the default for your "main object" and scaling everything based on that.

Also, the terrain is not measured in meters, it's measured in units like everything else.

Mass is KG, it's that simple man.... heh! :)

Time is time (seconds, as in the real universe). Distance is meters. That means velocity is m/s.

And that means Force, Acceleration, and Torque indeed all also use normal S.I. units.

It would be .. crazy .. madness! .. to try to work on a project (with cars, whatever, any vehicles, any real-world-like elements) .. unless everyone was simply working in the same units (ie ... S.I. units) for torque, power, force, friction, acceleration, etc etc.

Why?!

(Imagine trying to do car suspension!!!! if - for what reason?? - everyone wasn't using ordinary units - hell! Discussions would be unbelievably confusing. Aircraft etc, all the same.)

Eric, every time we discuss this you say the same thing..!! "1 to 10 collision is same as 2 to 20 in physx" .... utterly true of course, but every time I gotta point out that the whole, err, gamut of units everyone on the project is using should be just normal units.

FOR SURE, in like candy crush you could use any old abstract units, but really EVEN THERE .. would you? (Why?) I was just doing a scrabble-like board where you push around blocks like that, and it was unbelievably easier (for me personally, and everyone) to just use totally real units. (ie, how much would this really weigh in real life, one could talk about that etc.)

Another critical point, you make is that (of course) you have to be concerned about the "decent range" of the "mass" value in physX, so sure, that's a specific issue. (I've never encountered this, but I'm sure it's the case - but it's arcane and not relevant to the point at hand.)

Here's one you'll hate man. I love using physics, physX that is, for UI. So my buttons, sliders, whatever, use springs, gravity etc. I find EVEN THOSE it's tremendously easier if you use real world units! Heh!

All this being said, it is utterly essential that everyone understands precisely your point ... of course "1 to 10 collision is same as 2 to 20 in physx". But then similarly you can just make your models any old size. But it all goes to hell unless one just uses normal units.