A method determines fill level data of an elevator car. The method includes: obtaining image data of the interior of the elevator car; determining the fill level data of the elevator car from the obtained image data by applying a pre-trained fill level classification model; and providing the determined fill level data of the elevator car to an elevator control system for further elevator use. The disclosure relates also to a fill level determination system, an elevator system, a method for training a fill level classification model for determining fill level data of an elevator car, computer programs and computer-readable mediums.