The dimensions are listed in BGG. Go to the game page, click on Versions, and then click on "Show Dimensions" shows "Size: Medium Rectangle (e.g. Agricola) · 12.40 x 8.90 x 2.20 inches or 31.5 x 22.6 x 5.6 cm"
Just checked my box and it looks like the dimensions got entered wrong, the main difference being the box height. The box dimensions are 12 X 8.9 X 4.1 inches.