Weigh Habitats Offsetting Locational Effects Act of 2018 or the WHOLE Act of 2018 This bill amends the Endangered Species Act of 1973 to revise the process by which the Department of the Interior or the Department of Commerce, as appropriate, reviews an agency action to determine whether the action is likely to jeopardize the continued existence of an endangered or threatened species or result in the destruction or adverse modification of the critical habitat of the species. Specifically, the bill requires the appropriate department, when making such a determination, to consider the offsetting effects of protection or conservation measures that are already in place or proposed to be implemented as part of the action.