Depends on what type of chicken it is. There are some types where the male and the female have a distinct difference as chicks , like the black sex-link male has a white spot on its head-the female does not. I have had some luck sexing day-old chicks by looking at their wings. You can only do this to one or two day old chicks. The wing feathers on the pullets are longer than on a cockerel of the same age. Last year, I picked 13 chicks as pullets...only 2 came up as roosters! There are several videos on you tube that show this method. Good Luck!