How long do helium balloons stay inflated?
Actual results will vary based on factors such as temperature, latex quality and the exact amount of helium used, but a typical 11-inch latex balloon will stay airborne for about 18 to 24 hours. A Mylar balloon, which is less porous than latex balloons, can stay afloat for up to 3 weeks, or even longer.
If you want your latex balloons to last longer, you can use the product Hi-Float on the inside of the balloon before inflating it. Hi-Float will add a protective shield, reducing the amount of helium that escapes.