I am fairly sure that this is a boy. My other two leghorns do not have the red wattle type things under their chin, and their combs are much smaller and not red at all. Is it a boy?
Looks like a rooster. Another picture would be helpful if you had one. I added 6 hatchery Brown leghorns this spring. 3 boys 3 girls. The girls do not still have wattles to speak of and virtually no combs at 11 weeks old. I saw the difference very clearly at 7 weeks old. The tail feathers really stood tall on my girls. The tail feathers were long on the boys and had that deep green/black coloration to them. The white earlobe was visible bright and clear on the roosters at 7 weeks old. However the hens are taking longer to show off their white dots on their ears.
Looks like a rooster, but I really can't make an educated guess from that picture. And it's hard to tell the sex when we don't know the age of the bird.
Really there shouldn't be any comb development right now if it were a hen...
If that photo is of a 3 month old then I would change my guess to a pullet. It doesn't look 3 months old in that photo to me though.
A brown Leghorn roo will be bigger and different in feathering by 2 months old. Totally noticeable. If that photo is a 3 month old then I would say, hen.
that is a PULLET! a male would be showing black on breast already. She is all hen colored. Look at pictures of young or adult male Light Brown leghorns or Welsumers to see the big color differences at this age.
sometimes people fall into the trap of looking at comb/wattles only without considering rest of the bird.