What are the dimensions of the 6iE custom background image?

The 6iE custom background screen dimensions are 3 1/2 inches diagonally. However, image scaling is not required thanks to auto-scaling when you upload your custom background.

Tips: Make sure the image you use has a 4:3 landscape aspect ratio (standard camera aspect ratio), to avoid the image being stretched when we scale it. We accept jpg, png, HEIC. Not PSD etc.

Related:

How do I upload a background to my thermostat using the MyHeating app?