How much lift does the average latex helium filled party balloon produce? How much lift does the average helium filled party balloon produce? (not including any extras like ribbon string)
 A: The mass difference of the air it would have contained and the Helium it does = the volume of the balloon multiplied by the difference in density of the helium and air.
Suppose the balloon is spherical and 12" in diameter (physicists can only do the arithmetic for spherical objects, and preferably in a vacuum).
That gives it a volume of $\frac43 \pi r^3$ so annoyingly mixing units, $\frac{4}{3} \pi\, (0.15\:\mathrm{m})^3 = 0.014\:\mathrm{m^3}$
Air has a density of $1.2\: \mathrm{kg / m^3}$ at room temperature and pressure and Helium $0.176\: \mathrm{kg / m^3}$.
So your balloon has a lifting capacity of $0.014 \cdot (1.2-0.176) = 0.014\:\mathrm{kg}$
A: As an experimental answer, for 12" latex balloons, I could lift about 5 grams (in addition to the balloon).  It of course will depend on how full you fill the balloons.
A: Another experimental answer weighing in around 5 grams: http://www.cockeyed.com/science/helium/helium.shtml
An 11" diameter helium balloon with 26 inches of ribbon lifted itself plus 4.8 grams, a total mass of 8.3 grams. It displaced 8.2 liters of water, so that matches up reasonably with a theoretical lifting capacity for helium of 1 gram per liter.
A: In the case of hellium the pressure exerted by the rubber is negligible. However, when my mad scientest buddies and I tried using methane, we could only get lift if we used dry cleaning bags which did not compress the gas.
