An A2 size envelope is 4-3/8" x 5-3/4". An A2 envelope is the perfect size to fit homemade cards. An 8.5x11 sheet of paper folded in quarters will fit in this envelope. These envelopes have a unique deep flap adding fun to every letter and invitation! We stock these envelopes in packages of 25 and some options in boxes of 250. These envelopes are acid free.