Not sure if they mention the dimensions, but they are 15" high, 30" long, and 15" wide. Inside, it's 14.5" wide, 29.5" long, and 13.5" high. 
Great bench for the money. We got it in blue. It comes flat and has a bottom that can easily be dropped down to construct the bench. I will buy them in other colors to create storage in a house we rent for the following year. I already have a half dozen towels in it, and there is room for 6-8 more. The towels to the right are HUGE bath sheets for the pool. 
The only drawback/neg is it is a bit fishy smelling at 1st. I did not take away a star bc the smell went away quickly after taking it out of the box. Mind you, it is summer, we live in FL, and I'm a chef/super smeller (sensitive olfactory)