This report provides guidance on how countries should estimate and report to the UNFCCC their PFC emissions from the primary aluminium production process, which is the largest anthropogenic source of emissions of two PFCs: CF4 and C2F6. Emissions of CF4 and C2F6, therefore, vary significantly from one aluminium smelter to the next, depending on pot technology and operating procedures. The IPCC guidelines recommend multiplying aluminium production by CF4 emission factor and C2F6 emission factor.