Thumbnail Size

[ebrays]

Hi - does anyone know AGOL's new thumbnail sizing?

Since the June update last night the 600x400 pixel custom thumbnail templates I've made don't fit now and being a real pain trying to guess and get my thumbnails to fit properly. Can't find recent documentation on correct sizing. Or any advice.

Thanks!

[Joshua-Young]

The new ratio appears to be 400x400 pixels, so now all our thumbnail images have to be squares. 

[ebrays]

Haha the answer was right in front of me! Thanks Joshua 

[StephanieW · Accepted solution]

Hi @ebrays this was documented as BUG-000177465: Following the ArcGIS Online June 2025 update, an item's thumbnail now defaults to 400 x 400 pixels when it used to be 600 x 400 pixels and is under review.

[ebrays]

Thank you Stephanie