Once an image has a width of over 1080 pixels, Instagram will downsize it, which results in a loss of details.
However, according to Instagram, the maximum image size they accept without making their own adjustments is a width of 1080px. I normally upload my images to multiple platforms so I choose to use a standard size of 1920px on the long side. Personally, I don’t worry too much about this. There are many discussions about what’s the ideal image size for images uploaded to Instagram.
A post shared by Christian Høiberg Choose the right size and format
