1500 cubic inches 13.5 L x 8 W x 15 H. Its like a deluxe grocery pannier, only its so much more. This is a great bag for errands, commuting drop your briefcase right inside, and visiting your favorite market. The easy on and off mounting, long handles and a shoulder strap make it convenient to bring inside, and a large cinch down flap keeps your stuff covered on the road. Cinch down flap keeps load covered and secure. Side straps adjust support and fold pannier closed when not in use. Inside zipper pocket for keys and cash.