Event Cover image resolution recommendation is wrong

When creating an event, the event system recommends a cover image "that's at least 800px wide and 400px tall"

When you make a picture of that resolution it is too high and the top and / or bottom is cropped off.
It should recommend the correct resolution for the image. I checked the image after it gets cropped and its 800 x 320.
It should recommend an image size of this resolution / ratio.