If you haven't already you will get an email from eBay requesting you to evaluate the support you received.
I asked Ebay support (almost impossible for me to find) what the maximum picture file size is for use with an item description. This is their response:
Hello,
Thank you for writing eBay support regarding picture size. My name is
Luke and I will be happy to assist you.
eBay Picture Services displays images at 400 pixels on the longest side,
so please make sure that your image is a "jpg" file at least 400 pixels
pixels on the longest side, no more then 800 pixels pixels on the
longest side and no more then 900k in size if using the Full Featured
version of eBay Picture Services (no more then 500k in size if using the
Basic version). eBay Picture Services displays images at 400 pixels on
the longest side but does not enlarge the size of any image. However,
it will edit your file size down, if needed. If you reduced the size of
your image it may appear smaller than you would like. Please remember
that you do not need to manipulate your image prior to loading it using
the Picture Services upload page, Picture Services will do that for you.
Thank you for giving me the opportunity to be of assistance to you.
Regards,
Luke
eBay Customer Support

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