I try to keep this as up-to-date as possible, but Facebook has an unpleasant behavior of making unannounced modifications then rolling them out gradually to customers to ensure that not everybody gets them at the same time. If you've observed something that's transformed, please let me understand in the comments so I could check out and also upgrade as required.
What Are The Dimensions Of A Facebook Profile Picture
Facebook profile Photo Size
The profile Image is the smaller, square at the bottom that's to the left of the cover image. It used to overlay the cover photo's bottom left corner, but in the most up to date format, it has been moved to its own area in the top left of the web page.
Your Web page's profile image:
Screens at 170x170 pixels on your Page on computers, 128x128 pixels on mobile phones and 36x36 pixels on many attribute phones
For profile images and cover photos with your logo design or text, you might obtain a better result using a PNG file.
Keep in mind that your Page's profile image will be cropped to a round form in advertisements and also articles, yet will remain the exact same square form when people see your Page.
Profile Image on the Timeline
The profile picture that shows up next to your name on comments as well as messages is the same image however is automatically reduced to 40px by 40px.