Classic and PhotoX backpacks have a total volume of 22 liters.  Classic and PhotoX backpacks measure 18.1" (Height) x 11.8" (Width) x 6.3" (Depth) Space + has a total volume of 30 liters. Space + backpack measure 18.1" (Height) x 11.8" (Width) x 8.7" (Depth)