Bai ɗauki kwarewa da yawa ba kafin ka fahimci cewa ainihin girman katako masu girma sun bambanta da ƙananan masu girma wanda aka tsara su. Alal misali, 2x4 shine ainihin 1-1 / 2 "ta 3- 1/2" a girman, yayin da kwamiti 1x6, lokacin da aka aunawa, ya nuna cewa kawai 3/4 "x 5-1 / 2" a ainihi size. Kuma wannan gaskiya ne ga mafi yawan katako da ka siya - za a rage ainihin matakan da za a rage daga ƙaddamar da katako.
Me yasa hakan yake haka? Ga wani takardun da Ma'aikatar Harkokin Kiwon Lafiya na Amurka ta samar da shi mai suna Tarihin Yard Lumber Size Standards (Satumba 1964). Duk da yake wannan takardun ya fi shekaru 40 a yanzu, yana ba da tarihin ban sha'awa lokacin da kuma me yasa aka rage katako daga noman jama'a (2x4, alal misali) zuwa ainihin masu amfani da ita a yau.