An applicator for applying a product to hair, especially a hair colouring product, including: at least one first row of teeth extending longitudinally over a distance l1, from a first application face of the applicator; and a plurality of second rows of teeth, extending longitudinally over a distance l1, from a second application face of the applicator, which is arranged opposite the first application face, the ratio l1/l2 being lower than or equal to 0.75.