The Open Graph image size
The Open Graph image (og:image) is the picture shown when your link is shared on Facebook, LinkedIn, Slack, Discord and many other apps. 1200 x 630 pixels, a 1.91:1 ratio, is the size that displays well almost everywhere; much smaller images fall back to a small thumbnail or none.
How to make a good Open Graph image
Keep the important part in the middle, since some apps crop the edges. Use large text, high contrast and your logo. PNG or JPEG under 5 MB is accepted by every major network.
Questions
What size is a Open Graph image?
The Open Graph image (og:image) is the picture shown when your link is shared on Facebook, LinkedIn, Slack, Discord and many other apps.
What is the best Open Graph image size?
1200 x 630 pixels. It keeps the 1.91:1 ratio that Facebook, LinkedIn and most apps use for large link previews.
How do I check which image my page shares?
Run the page through the social preview checker, which reads the og:image tag and shows the card.
Is my image uploaded anywhere?
No. The image is read and resized in your browser; nothing is sent to a server.
How does the resize work?
It scales the image to cover the target size and crops the overflow evenly from the edges, so nothing is stretched.