When can you find out gender of baby?

It depends on the determination method. More invasive laboratory tests can tell you within a couple of months pregnancy. Ultrasounds would give an indication within 4 months or so. The "old fashioned method" of inspecting the crotch can be used as soon as they are born. All the methods have their shortcomings, which could include fetal harm (during amniocentesis) or making the wrong determination.