A balloon fill gauge for a balloon made of elastomeric expanding material has a base sheet with balloon filling indicia thereon that is temporarily tackable on to the balloon face material. An indicator tab with two ends having one end temporarily tackable onto the balloon material has its other end slideably interlockable with the base sheet. An indicator mark on the tab is alignable with the balloon filling indicia to indicate when the balloon is full as the tacked base sheet and tacked indicator tab move apart during the filling of the balloon. The balloon fill gauge alternatively may have an elongate non-stretchable indicator tab having two ends tackable onto the balloon material which physically acts to visual indicate when the balloon is full by snapping in two, popping off the balloon or changing color. Alternatively, the balloon filler gauge may include a base sheet with a balloon filling indicia temporarily tackable onto the balloon which is indexed with an expansible indicator ink mark on the balloon alignable with the filling indicia to indicate upon expansion of the ink mark when the balloon is full or the ink otherwise changes color.