No Transcoding: We recommend keeping static MMS images files under 740Kb. Sinch Transcoding: We recommend keeping static MMS images files under 1Mb.
Recommended Images Dimension for Static MMS Images
The optimal image size across all devices has an aspect ratio of 9:16. We recommend 640px by 1138px or 1080px by 1920px.
Image Design Considerations for Static MMS Images
When an MMS image is delivered to a phone there are typically two ways the content is displayed. The content is displayed in the message conversation thread within a message bubble and then when the image bubble is tapped, the content is displayed in a full screen view. When the image is displayed within a message bubble, there are portions of the image cut off from view. It is therefore important that any image be designed with the “content of interest” within a more restricted areas of the image so that it is readable from within the conversation view.
For Images 640px by 1138px: Avoid adding content of interest on the top 129px and the bottom 89px. For Images 1080px by 1920px: Avoid adding content of interest on the top 219px and the bottom 150px
Additional best practices for Static MMS Images
Image files in a .jpg format tend to render faster and are supported on more devices than .png files.
Do not use transparency in your image file. Transparent sections of an image may be rendered, white, black or in the message bubble color. There is no consistency behavior between device client versions.