Facebook Post Sizing Guide

I was told the correct size for posts on facebook was 400 x 400px and I believed every infographic on the planet.
But, according to Hugh Briss whose company Social Identities designs social media graphics and backgrounds — and does a darn good job of it I might ad.Facebook Post Size 2013 jenlew.com

Well, Hugh say’s facebook posts should be 1024×768 to account for permalink page dimensions and he’s right.