Air has no weight when it is free to move from one place to another, but it contains weight when it is filled inside any container because the air inside a container compresses by the walls of balloons, which gives weight to the air inside the balloon.

Does air have weight?

Air does, in fact, have weight, and here's a simple way you can prove it. You'll need two identical balloons, a string, and a dowel. ... The side with the inflated balloon hangs lower than the other side. You have demonstrated that air has weight!

How does air have weight and mass?

It might not seem like it, but air has weight. ... This is because the parcel of air is embedded in surrounding air that has the same density (mass per unit volume). But imagine that we remove that parcel of air from the atmosphere...the atmosphere would then weigh very slightly less.