Sayyidah Umm Kurz (may Allah be pleased with her) narrates: I asked the Messenger of Allah (peace and blessings be upon him) about the aqiqah. He (peace and blessings be upon him) said: "For a boy, two equivalent sheep, and for a girl, one sheep."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 21864