As the marketplace for Hermès bags grows with new collectors obtaining their initial Birkin each day, 1 element of Gold’s latest rise could be attributed to the initial Birkin theory, which states:The Birkin bag is available in 4 sizes: 25x19 cm, 30x23 cm, 35x28 cm and 40x31 cm. There's a larger sized journey bag Model that may be fifty cm vast.