You can upload a background image with a maximum size of 800KB. The format can either be JPG, GIF, or PNG.
As for the ratio, the recommended size is 1920 x 1080.
🗄️ Old dashboard:
The background image size depends if the image is set as a full-screen background or as the cover image.
If it's set as a full-screen background, the usual width and height is 1920 x 1080.
If it's set as a cover photo, the image can be 1536 x 250.
In both cases, please make sure the file size of your image is less than 200 KB for better performance and experience in your form.