How Long Do Balloons Stay Inflated?

One of the keys to a smooth-running party is doing as much of the prep as possible ahead of time. That can include having your cakes and refreshments made up and refrigerated the day before, or catering ordered a week or more head of time. When it comes to balloons, though, there's a limit to how far ahead you can work. Depending on the type you choose, your balloons can start to look tired in as little as a few hours.

Balloons come in two main varieties: rubbery balloons made of a substance called latex, and foil balloons made with Mylar. Latex balloons, which are more porous, allow air to escape faster, and therefore don't stay inflated as long as Mylar balloons do.

Balloons can be filled with either air or helium. Helium has smaller molecules than air — that's what allows it to float — and the smaller molecules are released from the balloon faster, causing the balloon to deflate more rapidly than an air-filled balloon would.

Many factors can play a role in a balloon's life expectancy, so vendors are usually careful to give approximations rather than a firmly guaranteed time.

Size plays a major role in the inflation time of a balloon, for example. An 11- or 12-inch latex balloon filled with helium might last 8 to 10 hours indoors, while a 24-inch balloon might last up to 24 hours. The quality of the latex balloons also plays a role. The higher quality they are, the less air the balloons allow to escape and the longer they remain full. In comparison, a 15-inch foil balloon will stay aloft for 26 to 30 hours, while "jumbo" sizes of foil balloon can keep their lift for up to two weeks.

The temperature and humidity on the day of an event can also affect balloon inflation. Cold weather particularly can cause molecules to shrink and make balloons smaller, while hot weather can speed up molecule movement and cause air to escape from balloons more quickly.

To help prevent your helium-filled latex balloons from falling, you can treat the inside of them with a material called Hi-Float before inflating them. Hi-Float coats the inside of balloons to prevent air from escaping and can increase float time by one or two days.

In addition, buy the highest-quality latex balloons you can find, and avoid under-filling them. The less air they have to begin with, the more quickly they will wilt. Tie a tight knot in the inflated balloons to prevent any extra air from escaping.

If the weather is going to be particularly hot and humid, opt for larger balloons with a longer float time to make up the difference.

If you'll be using balloons for an event, use conservative estimates for their inflation time, and wait as long as possible before the start of the event before inflating the balloons. That way, you'll be sure not to have droopy decorations at the end of the party.