Photo Size in Social Network

Facebook

• Cover Photo 851 x 315 pixels
• Profile Picture 180 x 180 pixels (Preview 160 x 160 pixels)
• Profile Picture on the Timeline / Post / CommentScale to 32 x 32 Pixels
• Shared Link Thumbnail 484 x 252 
• Uploaded Photos 2048 x 2048 pixels
• Uploaded Timeline Photo Thumbnail 504 x 504 pixels [max]

Twitter

• Header Photo 1500 x 1500 pixels
• Profile Picture 400 x 400 pixels
• Other 880 x 440 pixels

Google+

• Cover Photo 2560 x 1440 pixels
• Profile Photo 250 x 250 pixels
• Other 800 x 600 pixels

YouTube

• Profile Picture 800 x 800 pixels
• Channel Art 2560 x 1440 pixels [Max Size 2 MB]
• Custom Thumbnail Video 1280 x 720 pixels

Instagram

• Profile Picture 161 x 161 pixels
• Recommend Picture 640 x 640 pixels