delivering catalog images on white background-72dpi but what pixel x pixel?

[archipirata]

That sounds like a reasonable size to me. The on-white product images we output are 2000-3000 pixels on the longest dimension. We output that because even if the initial view is smaller like 500 pixels, most e-commerce websites (Amazon, etc.) demand larger files so they can enable zooming in.

Example here, when you click on the images you get the giant zoomed in versions: https://www.amazon.com/StewMac-Precision...01HYB7ZGE/