Schema.org neither requires nor recommends specific image dimensions. For an ImageObject
, you may specify the image’s height and width with the height
and width
properties.
Consumers of the data would have their own rules, if any at all.
In case of Google Search
tl;dr:
For some Rich Snippets that use the image
property, no dimensions are specified.
For other Rich Snippets that use the image
property, Google specifies
at least 160x90 pixels and at most 1920x1080 pixels
For Google Search, the documentation for their Rich Snippets is at https://developers.google.com/structured-data/rich-snippets/.
Here’s what they define for their current Rich Snippets that make use of images:
Products → image
The URL of a product photo. Pictures clearly showing the product, e.g. against a white background, are preferred.
Recipes → image
Image of the dish being prepared.
Videos → thumbnailUrl
A URL pointing to the video thumbnail image file. Images must be at least 160x90 pixels and at most 1920x1080 pixels. We recommend images in .jpg, .png, or. gif formats. All image URLs should be crawlable and indexable. Otherwise, we will not be able to display them on the search results page.
Articles → image
:
A URL, or list of URLs pointing to the representative image file(s). Images must be at least 160x90 pixels and at most 1920x1080 pixels. We recommend images in .jpg, .png, or. gif formats. All image URLs should be crawlable and indexable. Otherwise, we will not be able to display them on the search results page.
Only marked-up images that directly belong to the article should be listed in this property. If there are multiple applicable images, please list them all with the important images first.
(Google also has non-Rich-Snippet uses for Schema.org markup, e.g., for their Knowledge Graph: Organization’s Logo and Corporate Contacts use the logo
property, but they don’t specify any dimensions.)