Facebook Photo Sizes
- Facebook Cover photo size: 851px x 315px desktop / 640 pixels wide by 360 pixels mobile
- Facebook Profile photo size: 180px x 180px (shows up as 160×160 on desktop, 128×128 pixels on smartphones and 36×36 pixels on most feature phones)
- Facebook Shared Image: 1200 X 630
- Facebook Group Cover photo size: cover photo must be at least 400 pixels wide and 150 pixels tall
- Facebook Event Cover photo size: 1920 by 1080 pixels
Twitter Photo Sizes
- Twitter Header size: 1500px x 500px
- Twitter Profile size: 400px x 400px
- Tweeted Image size: 440 x 220 pixels
Google+
Google+ Photo Sizes
- Google+ Cover photo size: 1080px x 608px
- Google+ Profile photo size: 250px x 250px
- Google+ Shared Image size: 497px x 373 or 150 x 150
Pinterest Photo Sizes
- Pinterest Profile Photo size: 165px x 165px circle
- Expanded Pin – Maximum pin width: 735px x unlimited
- Pinterest Board cover: 217px x 146 pixels
LinkedIn Photo Sizes
- Background photo: 1536 x 768
- Profile photo: 400 x 400
- Post image (open graph): 1200 x 630
Instagram Photo Sizes
- Instagram Profile Photo size: 110px x 110px minimum
- Instagram Photo size: Upload a photo with a width of at least 1080 pixels
YouTube
YouTube Photo Sizes
- YouTube Channel Art size: 2560px x 1440px
- YouTube Video thumbnail: 1280px x 720px
- YouTube Channel icon: 800px x 800px image
Tumblr
Tumblr Photo Sizes
- Tumblr header size: 1100px x 500px
- Tumblr profile photo size: 128px x 128px
- Tumblr image post: upload an image of at least 300px in width, it will be automatically scaled to 540px width