Flickr Cover Photo Size

Flickr.com has a new lay-out which includes a wide cover photo on the Flickr Profile page. Try this size 1583 x 235 pixels. It has worked well for me. You could extend the pixel height too so you have room for height adjustment by using their drag tool

If you're feeling rather lazy about your Flickr profile page header then just choose - Edit Cover Photo and choose the largest photo you have in your Photostream; Flickr will just adjust this to fit the cover photo area.

What if I don't want to touch anything?
Not a problem. Flickr has existing header cover photo presets for those who don't mind having a stock photo on their header.

But I don't like the new Flickr layout. Same here. I don't like the photo I'm looking at, coming at me in "POP-UP" form. It will take awhile and a lot of getting used to the new Flickr site design.