This [wikia][1] lists different weights for the different forms.

 - As Banner he is 128lbs
 - As the Savage Hulk he weighed 1040-1400lbs.
 - As the grey Hulk he was 900lbs
 - As the merged, intelligent Hulk he was 1150lbs.

  [1]: http://marvel.wikia.com/Hulk_%28Robert_Bruce_Banner%29