This document details the perimeter selected for the evaluation of farm greenhouse gas, the types of greenhouse gases taken into account and the different direct and indirect estimated emission sources. The calculation methods (formula) are detailed for each greenhouse gas emission source, carbon stock variation, as well as the allocation rules of the impact of greenhouse gas between the various agricultural products of the farm. In the same way, the emission factors of each data item of the tool are grouped in a recapitulative table that provides the bibliographical references.