Rich cards can be driven by image size. Google provides the following recommendations for how to best use media in rich cards:
- Cards expand vertically to fit their contents. Rich cards have a minimum height of 112 DP and a maximum height of 344 DP. If the contents of a card are not large enough to fill the minimum card height, the card expands and fills the extra height with white space.
- Media in rich cards must fit one of three heights:
- Short: 112 DP
- Medium: 168 DP
- Tall: 264 DP.
- Vertical rich cards - Vertical rich cards display horizontal media at the top of the card. Horizontal media should have an aspect ratio of 2:1, 16:9, or 7:3.
When you send media to a user, you should be respectful of the user's resources. When horizontal media has a 2:1 ratio, the optimal resolution for the media is 1440x720 px with a maximum recommended file size of 2 MB for images and 10 MB for video. The optimal resolution for the media's thumbnail is 770x335 px with a recommended file size of 40 kB and a recommended maximum size of 100 kB.
- Horizontal rich cards - Horizontal rich cards display vertical media on the left or right side of the card. Vertical media should have an aspect ratio of 3:4.
When you send media to a user, you should be respectful of the user's resources. When vertical media has a 3:4 ratio, the optimal resolution for the media is 768x1024 px with a maximum recommended file size of 2 MB for images and 10 MB for video. The optimal resolution for the media's thumbnail is 250x330 px with a recommended file size of 40 kB and a recommended maximum size of 100 kB.
Note: Carousels are a collection of rich cards – so when using carousels these recommendations also need to be taken into account.
