Where does the “mass” come from when potted plants grow?

Question

It’s easy conceptually to understand when animals eat physical food matter, it adds to their own body mass as they grow.

But potted plants grow 2x, 3x, etc their mass while the only (seemingly) inputs are Sun, water and occasional plant food. The soil level doesn’t seem to change much either, so where is the “material” coming from to make the plant bigger? Is it just from what I mentioned, and is there an easy way to understand how those things transforms to plant mass?

Edit: Thanks for all the answers! It unexpectedly helped me understand how plants capture carbon from the air and “store” it physically. I have a new appreciation for my houseplants 🪴

In: 8561

Answer 1

CO2 from the air. This is ultimately the material plants use to build most of their mass.

That’s really the long and short of it.