Visually Sexing Your Cockatiel is possible to most mutations except two, the Whiteface Lutino aka "Albino" and the Pied. These two radically eliminates the color markings to identify the female (albino) or mixes up all the color pattern (Pied) to provide proper identification.
Visually sexing your cockatiel is reliable after the completion of the first molt, which takes about 6-8 months of age. Before the first molt all of them look like girls.
The cock will have a bright yellow face mask with prominent cheek patches (except the whiteface). The hen will have a yellow face but of little surface area with the body color(usually gray) interloping parts of it including the cheek patch making it look duller than the male.
Barrings remain underneath the tail of the hen while they are absent after the first molt of the male.
Like the barrings, female cockatiels retain their spots under their wing where they are shed off by the male during maturity.
These spots and barrings are present even in the lutino. A bright light source will be necessary to visually identify the yellow/white barrings.
The Pearl's scalloped design while slowly shed off by the male during its first year while it will remain prominent in the female.
Combine these visual tips with your cockatiel's behavior and you have a relatively high chance of identifying the sexual orientation of your cockatiel.
