Total of four compartments:

•  Main compartment: 18″ x 10″ x 5″ with one zipper and one mesh pocket.
•  2nd compartment 15″ x 8″ x 2″
•  Front top compartment: 4″ x 7″ x 2.5″
• Front bottom compartment: 10″ x 8″ x 2.5″
• Hydration compatible
• 18″ x 10″ x 10″
  1362 in³