I’ve kinda been wondering this for a while. I haven’t seen any standard for rigidbody mass, whether it be for a car, crates, or other things. So I’ll look to other Unity users.
What values do you usually use for your various objects?
How could there be a standard value for mass? Heavier things have higher mass; lighter things have lower mass. Use what works and/or is appropriate for your game. If in doubt, use something that would be a reasonable guess for the real-world mass of a similar object.
I read in some part of the documentation that Mass usually shouldn’t exceed 10 units. That leads me to wonder what this 10 units actually is, and what others usually use as their cap.
With the gravity set to the default value, one unit is equivalent to one kilogram. However, it is common for physics simulations to have completely unrealistic masses and forces. If they are all in the right proportions then the game should still look OK regardless of the actual values.