Balloons float because they are filled with helium! Balloons can be filled with different types of gas. The air we breathe is made up of lots of different gasses. ... The helium wants to float up, up, and away from the surface of the Earth — so your helium-filled balloon wants to float up, up and away too!

Do all helium balloons float?

All balloons can surely be filled with helium but not all of them will float.

Why are my helium balloons not floating?

The main reason a balloon wont float is if not enough helium has been added, check the correct size of your balloons and add helium until the balloon reaches its correct size.