My old steely says 1.8kg on it, but it weighs in at about 2.2kg! :O
That weight does not include the regulator that is fitted.
And some info about the weight of air.......
"Absolute Fahrenheit is used to calculate air weights at different temperatures. It is the number of degrees above Absolute Zero, which is around minus 460 degrees Fahrenheit. As prime example, 48 Fahrenheit is the same as 508 Absolute Fahrenheit, and 175 degrees Fahrenheit is the same as 635 Absolute Fahrenheit.
At 48 F (508 A) a cubic foot of normal pressure sea level air weighs almost exactly 1 1/4 ounces. Heated by 127 degrees, to 175 F (635 A), it weighs almost exactly an ounce, or 4/5 of its original weight, for a gross lift of a 1/4 ounce per cubic foot."
Quoted from a hot air ballon web site.
Russ