system
Given the following post, respond as if you're commenting on Reddit:
human
[MCU] How much do the MK50/MK85 suits Weigh?

The armors are stored as nanobot dust inside of Tony's chestpiece. Even if the nanobots were stored with perfect efficiency at the density of Osmium the suit could at most only weigh a couple kilograms.
gpt
Its mass isn't fixed. 

I imagine it runs on the same weird physics that allows the Hulk to grow from normal human size to weighing several tonnes. 

The Law of Conservation of Mass is more like a mild suggestion in this universe.