Hermes Birkin bags are sold in a range of sizes. Each one may be made to order with different customer-chosen hides, colour, and hardware fixtures. There are also other individual options, such as diamond encrusting.

The bag comes in a variety of hides, such as calf leather, lizard, and ostrich.[19] Among the most expensive used to be saltwater crocodile skin and bags with smaller scales cost more than those with larger scales. Each bag is lined with goat-skin, the colour of the interior matching the exterior. Prices for the Birkin bag depend on type of skin, the colour, and hardware fixtures.[20]

Sizes range from 25, 30, 35, to 40 centimetres (10″, 12″, 14″ to 16″), with travelling bags of 50 and 55 centimetres (20″ and 24″). It also comes in a variety of colours such as black, brown, golden tan, navy blue, olive green, orange, pink, powder blue, red, and white.[20]

The bag has a lock and keys. The keys are enclosed in a leather lanyard known as a clochette, carried by looping it through a handle. The bag is locked by closing the top flaps over buckle loops, wrapping the buckle straps, or closing the lock on the front hardware. Locks and keys are number-coded. Early locks only bore one number on the bottom of the lock. In more recent years, Hermès has added a second number under the Hermès stamp of the lock. The numbers for locks may be the same for hundreds of locks, as they are batch numbers in which the locks were made.[19]

The metallic hardware (the lock, keys, buckle hardware, and base studs) are plated with gold or palladium. Detailing with diamonds is another custom option.[19]

Hermès offers a “spa treatment,” which is a reconditioning treatment for heavily-used bags.[21]

A “Shooting Star” Birkin has a metallic image resembling a shooting star, stamped adjacent to the “Hermès, Paris Made in France” stamp, that is in gold or silver to match the hardware and embossing. Rarely, the stamp is blind or colourless, if the bag is made of one or two leathers onto which no metallic stamping is used. Sometimes, Birkins or other Hermès bags may be made by independent artisans for “personal use”, but only once a year. Every bag bears the stamp of the artisan who made the bag. These identifications vary widely, but are not different for every bag made. Finding stamps of more than one artisan on a bag occurs because the stamp is not a serial reference. Fonts and the order of stamping may vary, depending on the artisans.[21]