As calculating the potentially large number of pages can affect this call's performance, and since the actual number of products returned per page can vary in each response, we cannot provide a precise total page count. Therefore, this is an estimated page count based on TotalProducts and other factors, such as the number of records eBay's search engine has examined so far in the product database. Once PageNumber approaches or exceeds this page count, we examine more records in the database and we may recalculate this value. If you estimate the number of pages yourself by using TotalProducts, EntriesPerPage, and MaxChildrenPerFamily (which is also an approximate value), your result will not necessarily match ApproximatePages.
See the
Field Index to learn which calls use ApproximatePages.