If you want to quickly make an image for Twitter, Instagram, Facebook, Google+ or Pinterest, our handy cheat sheet will tell you the size.
Even better, with a copy of Adobe Illustrator you can edit the downloadable pdf which has artboards set up for every size you might want. This handy resource will save you lots of time and frustration. Download it here, and please share it!
The sizes are correct on the day of posting in May 2016. They came courtesy of Sprout Social.