Our fragrance oils are always filled by weight, not by volume. This means that 2 different fragrance oils can be filled to different levels due to the thickness of the chemicals used to create the fragrances. Some chemincals are heavier and fill less volume, while others are lighter and fill more volume. All of our fragrances will contain the weight of fragrance stated on the bottle.
Since candle formulations are measured by weight and not by volume, the fill level does not have any impact on how far the fragrance will go (i.e. a fragrance that is fuller in volume will scent the same amount of wax as a bottle with less volume of fragrance).