How to display an object with specific dimension?

Let’s say I want to display a cube of 1" on HMD VR using Unity that is perceived equally to the player using VR. In other words, what i declared as 1" in unity is same as 1" in real life. I’m a newbie in Unity, plz help : )

Possible duplicate of: Unity unit scale? - Unity Answers and others.

The default in unity is meters, which is assumed by Physics default configuration. I would recommend to stick to meters to avoid problems and get realistic behavior.