Xa ukhetha izibane zasezitratweni, ukuphuma kwe-lumen yenye yezona parameters zobugcisa zibalulekileyo ekufuneka ziqondwe. Ii-lumen zilinganisa ubungakanani bokukhanya okubonakalayo okukhutshelwa ngumthombo wokukhanya. Ngokungafaniyo ne-wattage, ebonisa kuphela ukusetyenziswa kwamandla, ii-lumen zibonisa ngokuthe ngqo indlela ukukhanya kwesitalato okukhazimlayo ngayo ngokwenene.