Scot is experiencing issues with images appearing too small when added to posts. SaraDev explains that the default image size can’t be specified, but the max image width and max image height can be set through the Admin → Site Settings menu. Images larger than the max width/height will be automatically scaled down.
SaraDev suggests that adjusting the image size before uploading, keeping in mind the maximum dimension, is the best way to ensure images are displayed as intended. She notes that changing the max image width or height in site settings won’t affect already uploaded images.
Scot’s image was scaled down from its original size due to the maximum allowed size on Meta (690x500). SaraDev recommends scaling the image to 690x500 to make it full-width, but this would alter the original dimensions.
Scot has confirmed that the maximum width he can use is indeed 690, as it is the default max width of any post on Discourse.
I am having trouble finding an answer for this issue. Images always appear too small when I add them to a post. It doesn’t seem to matter what size I make them. Is there any way to get Discourse to default the image sizing in posts to fill the width of the post and let the height fall wherever it would naturally at that size?
Thanks,
Scot
Example: The image below is the width of a post but it will appear smaller in the post. How do I make it appear at full size or at least as wide as the post if it is wider than the post width?
Because of the variety of image sizes that can be uploaded to a Discourse site, you can’t specify the default size that an image will be. However, you can set the max image width and max image height (in pixels) for all images on a site through the Admin → Site Settings menu.
Images that are originally larger than the max image width/height will be automatically scaled down to meet the max width/height requirements of the site. For example, the following image was originally 1207x186, but when uploading the image here, it automatically gets scaled to 690x106]:
It looks like this is what’s happening with the image you attached here, as the height of your image is getting set to 500 because the image is larger than the maximum allowed size for Meta (690x500).

You could to scale your image to 690x500 so that the image is full width, but this would also scale the image to have different dimensions than the original.

Adjusting the size of your image before uploading to Discourse, while keeping in mind the maximum dimension that the image can be, is the best way to ensure your images get displayed as intended.
Also, note that changing the max image width or height in the site settings will not retroactively impact the size of images that have already been uploaded to a Discourse site.