WUR udregnes kun for primæremballagen, og der foretages en beregning for alle produkter i et flerkomponentsystem (herunder kapsler, propper og håndpumper/sprayanordninger) ved brug af følgende formel:
WUR shall be calculated only for primary packaging and a calculation shall be made for every product within a multi-component system (including caps, stoppers and hand pumps/spraying devices) using the formula below: