12 inches wide and about 10 inches Tall and can hold a good amount of stuff. It has an internal zipper pocket as well as slots for pens and small open pockets. On the outside it has a zipper on the back as well as two pouches on the front and slim pockets on the sides. The strap is adjustable . The bag is a really good quality and I could see it lasting forever. It sells new for $122. Inside cloth liner shows signs of use, but no rips. Offers accepted.