The short answer for a Wyandotte chick
A young Wyandotte is sexed by its rose comb, judged on width and colour rather than height. A cockerel's rose comb grows broader across the skull, flattens and spreads, and takes on pink colour from roughly six weeks, while a pullet's stays a small, neat, pale bump that follows the curve of her head. Wyandottes are round, heavily feathered birds whose laced plumage is identical between the sexes, so the comb — read weekly, by eye and by fingertip — carries nearly the whole job until male saddle feathers arrive.
Working with a rose comb instead of a single comb
Keepers used to single-combed breeds misjudge Wyandottes at first because they wait for a comb to grow tall, and a rose comb never does. The Wyandotte's comb is a low, wide, fleshy pad ending in a small spike that points back over the head, and its sex signal is horizontal: males' pads broaden and coarsen, their surface texture roughens, and the colour moves from yellow-pale to definite pink. A pullet's pad stays narrow enough that the head still looks smooth and rounded in profile.
Wattles, legs, and the supporting evidence
In a young Wyandotte, wattles corroborate the comb: a cockerel's drop earlier, grow rounder and fuller, and redden in step with his comb, while a pullet's remain small folds of pale skin for weeks longer. Legs are a weaker but real sign — cockerels stand on somewhat thicker shanks and tend to plant themselves upright at the feeder, chest out, in the classic lookout pose. Body shape helps least in this breed, because both sexes are bred round and deep, and a plump pullet in full feather looks every bit as massive as her brother. The late, decisive sign is the same as in other breeds: pointed, shining saddle feathers draping a cockerel's lower back and pointed hackles at his neck, against rounded tips everywhere on a pullet.
A weekly routine that actually separates them
Sexing a young Wyandotte rewards a fixed weekly routine starting around week five. Handle each chick calmly, run a fingertip across the comb to gauge its width and texture, and grade it narrow, broadening, or broad before setting the bird down. Judge colour on settled birds in natural light, because a chick flustered by catching flushes red all over its face and can fake a week of comb progress. Keep the grades per bird, in order, and expect the cockerels to declare themselves by consistency — the same names at the top of the list three weeks running — rather than by one dramatic change.
Wyandotte-specific traps
One Wyandotte trap catches keepers of laced varieties: cockerels and pullets both grow their lacing, but young males often feather in patchier across the back and shoulders while pullets lace more evenly, and this patchiness gets mistaken for a sexing guarantee — it is a tendency, not a rule, and comb evidence should outrank it. Another trap is the early-pinking pullet in a warm spell, whose comb colours from heat and exertion; size and width, judged on a calm bird, separate her from a true cockerel. Judge the Wyandottes against each other only.
Using the answer as the flock matures
An early, honest sort of young Wyandottes lets you plan laying-pen places, line up homes for surplus cockerels, and avoid the scramble of discovering three roosters the week they start crowing in earnest. It also lets you watch the pullets' combs for the deep reddening that later signals laying readiness, a completely different milestone from the cockerel pink of week seven. Any Wyandotte chick that is undersized, hunched, or off its feed needs a health check and, if it does not bounce back quickly, a veterinarian — a stalled chick's stalled comb will quietly corrupt your sexing grades as well. Storing each Wyandotte's weekly comb grades in KinsLe through Care Teams keeps the whole brood's progress visible to everyone who handles them, and Care Teams' timestamped marks show exactly when each cockerel's comb began to broaden.