When you upload a picture to the MLS, if the picture width exceeds the following limits, the software automatically reduces the size of the picture proportionately.
The maximum width for property pictures is 400 pixels.
The maximum width for personal (agent) pictures is 200 pixels.
If your picture width matches or is less than the maximum, the system does not resize it during the upload process.
NOTE: Picture dimensions are listed in pixels, not inches, because they are displayed on screen rather than printed. MLS pictures have a resolution of 72 pixels per inch.
See also
Creating pictures that can be uploaded to the MLS