Inflated size: 28cm.  Inflated with helium or air

Inflated price for each normal latex balloon is $3 includes helium, Hi-Float and string. (Only available for pick up in store or*). 

Helium-inflated balloons are affected by extreme temperatures and high altitudes. The rule for temperatures is to slightly under-inflate balloons when moving them from a cool environment to a warmer one (as the helium will expand), and slightly over-inflate them when moving them from a warm environment to a cooler one (as the helium will contract). For example, moving helium-filled balloons from an air-conditioned room to one that's not or to the outdoors on a warm or hot day will result in the balloon expanding. Test the balloons to determine proper inflation in each circumstance.

Altitude effects the float time of latex balloons as helium has less lift in higher altitudes. Balloon will not float as long in higher altitudes, so larger balloons should be used. For more precise results, helium inflate various sizes and track the times they float at your altitude.