How It Works
Balloon

If I let a balloon go, how high can it get before it pops, and why?

Balloon
At sea level there is about one ton of pressure exerted on you by the air at all times.
This pressure comes from the 100 kilometres (60 miles) of air above weighing down the air below. As helium balloons rise, the atmospheric pressure drops as there is less air above, causing the balloon to expand.
This expansion will continue until either the gas inside the balloon is of equal density to the air outside the balloon, or it pops due to the latex not being able to stretch any more (the latter being the most likely scenario).

Find the answer to more baffling questions in How It Works magazine. Order it in print, download the digital version or subscribe today to ensure you never miss an issue!

Plus, take a look at:

Balloon popping science 

Why does helium make my voice sound high-pitched?

Slow-motion water balloon video