You tell a young Leghorn chicken's sex by combining feathering speed in the first weeks with comb and wattle development a little later, because no single sign in a white Leghorn chick is decisive alone. Leghorns mature early for a laying breed, which works in your favour: their differences show sooner than in slower, heavier breeds.
Feathering speed in young Leghorn chicks
Feathering speed is the first clue in a young Leghorn because pullet chicks typically grow wing and tail feathers faster and more evenly than cockerels from the same hatch. Look across the brood rather than at one chick: the birds whose wing feathers reach well along the body and whose little tails push out early are more often female, while slower, patchier feathering with a stubbier tail leans male. This is a tendency, not a guarantee, and it is strongest when you compare siblings raised together on the same feed and warmth. Mark your early guesses lightly, with a dab of safe chick-safe marking or a note of distinguishing habits, instead of separating anyone on feathering alone. Recheck as the birds grow, because a chick that feathered slowly can still surprise you, and Leghorn down gives no reliable colour difference to fall back on.
Comb and wattle growth in a young Leghorn
Comb growth is the clearest mid-stage sign in a Leghorn because the breed carries a large single comb that betrays males early. A young cockerel's comb grows taller, thicker, and distinctly pinker while a pullet's comb stays small, fine, and pale for much longer, and his wattles drop and redden ahead of hers too. Leghorn pullets do eventually grow a notable comb that often flops to one side in the adult hen, which is why timing matters: it is the head start, not the final size, that signals a male. Compare birds of the same age side by side in good light, since a whole pen flushing pink after a warm scramble can mislead a quick glance. Thicker legs and a more upright, alert stance support a cockerel reading, while a rounder, lower outline supports a pullet, but let the comb cast the deciding vote at this stage.
Feather shape and behaviour as Leghorns mature
Feather shape settles a Leghorn's sex as juvenile plumage is replaced, because cockerels grow pointed, glossy neck and saddle feathers while females keep rounded feather tips across the back. A young male's tail also rises into longer, curving sickle feathers, quite unlike the neater, fan-shaped tail of a pullet in this white, tight-feathered breed. Behaviour joins in later: cockerels begin tidbitting, dropping a wing in a little shuffle dance, and eventually attempting thin, squeaky first crows, while pullets stay focused on foraging and flock squabbles. None of these behaviours should be acted on alone in a young bird, since dominant pullets can be bold and theatrical too. The reliable answer is a stack of agreeing signs: feathering pace, comb head start, then pointed saddle feathers all pointing the same way.
What to avoid, and deciding what happens next
Avoid vent sexing a young Leghorn at home, because the technique needs hatchery training and a wrong, rough attempt can damage a chick for information patience would have given you free. Also avoid rehoming or separating birds on one early guess if they are living happily together, since Leghorn youngsters are flighty and every unnecessary catch-and-move session costs trust you will want when handling adults. Decide in advance why the answer matters: cockerels may face local keeping rules, will not lay, and can turn a quiet flock noisy at dawn, so a confirmed male needs a plan rather than a panic. If two birds remain ambiguous after their siblings are obvious, an experienced poultry keeper or vet can give a hands-on opinion. While you work through the signs bird by bird, KinsLe's Kinny can walk you through the same Leghorn checklist in the moment, so each call you make is recorded against that chick rather than remembered roughly later.