Capricorn: Determined Opinionated And Moody AF A perfect card for sending a birthday wish to the Capricorn people in your life. Capricorn celebrates birthdays December 22nd - January 21st. • Measures 4 x 5.5 inches • Printed on acid and lignin free white card stock (A2) folded • Brown Kraft envelope • Blank inside ready for you to write a personal message.