In the digital photography section sorta Q came up of Google Picasa size posting limits, https://forums.macrumors.com/posts/9337747/ this is test/"proof" s800 and s1600 can be posted/viewable.
(I could not find a "test section" sub-forum, so in-lieu of that post here)
Prior I could upload picts larger than s800 to Picasa but Google Picasa seemed to limit pict size displayed to s800.
Recently (and quietly) seems they have allowed posting up to s1600 size picts.
Image 800 pix wide via "s800" in url link, http ://lh3.ggpht.com/_FqTNmgNQHz8/S3aaMNxEcTI/AAAAAAAAJK0/Z9pc_2ANNsc/s800/_MG_3821.jpg
Image 1600 pix wide via "s1600" in url link, http ://lh3.ggpht.com/_FqTNmgNQHz8/S3aaMNxEcTI/AAAAAAAAJK0/Z9pc_2ANNsc/s1600/_MG_3821.jpg
(I could not find a "test section" sub-forum, so in-lieu of that post here)
Prior I could upload picts larger than s800 to Picasa but Google Picasa seemed to limit pict size displayed to s800.
Recently (and quietly) seems they have allowed posting up to s1600 size picts.
Image 800 pix wide via "s800" in url link, http ://lh3.ggpht.com/_FqTNmgNQHz8/S3aaMNxEcTI/AAAAAAAAJK0/Z9pc_2ANNsc/s800/_MG_3821.jpg
Image 1600 pix wide via "s1600" in url link, http ://lh3.ggpht.com/_FqTNmgNQHz8/S3aaMNxEcTI/AAAAAAAAJK0/Z9pc_2ANNsc/s1600/_MG_3821.jpg