Kalmar "kyandir ɗin ƙafa" raka'a ce ta ma'auni da ake amfani da ita wajen kwatanta adadin hasken da ke faɗowa a saman. An bayyana shi a matsayin adadin hasken da ke faɗowa a kan saman da girmansa ya kai ƙafa ɗaya, lokacin da hasken ya yi nisa da ƙafa ɗaya kuma hasken yana rarraba daidai gwargwado. Ƙungiyar ma'auni don kyandir ɗin ƙafa shine "fc".
