The lifespan of a helium balloon depends on various factors, including the quality of the balloon, the amount of helium used, and environmental conditions. On average, a helium balloon filled with regular latex or Mylar (foil) material can last anywhere from a few hours to several days.
Latex balloons are porous and allow helium to slowly escape over time. Generally, they can stay afloat for around 6 to 12 hours, but this duration can vary. Temperature, humidity, and altitude can affect the rate of helium loss. In colder temperatures, the helium may shrink, causing the balloon to deflate more quickly.
Mylar balloons, on the other hand, are typically more durable and have a better seal, so they can stay inflated for several days or even weeks. They are often used for special occasions and events where longer-lasting balloons are desired.
It's worth noting that over time, all balloons will eventually lose helium and deflate. Therefore, the lifespan of a helium balloon is limited, and its buoyancy decreases as the helium escapes.