An air cap for a spray gun, in particular a paint spray gun, having at least one central opening, which is delimited by a mouth, and two horns, each having at least one inner and one outer horn air duct and one inner and one outer horn air opening. The spacing between the front end of the central opening and an axis which perpendicularly intersects the central axis of the central opening and runs through the center of an inner horn air opening is between 0.6 mm and 2.6 mm. The spray pattern generated by the air cap has a longer core region and a steeper transition of the layer thickness between the external region and the core region, compared to conventional air caps leading to improvement in coating quality. A nozzle assembly and a spray gun, in particular a paint spray gun, can have an air cap having the above properties.