How long will your helium balloon last depends on what material it is made of
. Mylar balloons can hold helium for up to 2 weeks whereas latex balloons wear out sooner, within 24 hours. Both types are suitable according to the purpose in mind. If it's a one day event, it makes more sense to go in for latex balloons, however, if you need the balloon to be stationed for a longer period, mylar or foil balloons are the obvious choice. Besides, they can be refilled with helium, as and when required.