The sizes and specifications for LinkedIn company logos are:
Recommended upload size: 300 x 300 pixels (large logo), 60 x 60 pixels (small logo)
Aspect ratio: 1:1
Maximum file size: 4MB (large logo), 2MB (small logo)
File types: .JPG, .GIF, .PNG
The larger logo is your standard company logo that appears in the header of your company profile page and in the “Companies You May Want to Follow” section. The smaller logo is the brand image that shows up when your company is searched.