A common helium-filled latex balloon lasts from about 12 hours up to two days. However, the size, type of material, and presence of a sealant all affect the balloon's lifespan. The treatment and level of activity to which the balloon is subjected also affects how long it floats.
Generally, the larger a helium balloon is, the longer it lasts. A 90-centimeter latex balloon lasts about 12 to 36 hours longer than a 30-centimeter latex balloon does. A sealant called Hi-Float adds a week or two to the lifespan of latex balloons. Mylar balloons last for about three to four days before deflating slightly. These balloons still float for several more days after the slight deflation.