verb
to not take a proper measure of oneself; to overrate one's own abilities
世上最可笑的是那些“知識裏手”，有了道聽塗説的一知半解，便自封為“天下第一”，適足見其不自量而已。
世上最可笑的是那些“知识里手”，有了道听涂说的一知半解，便自封为“天下第一”，适足见其不自量而已。
shì shàng zuì kě xiào de shì nà xiē “ zhī shi lǐ shǒu ” ， yǒu le dào tīng tú shuō de yī zhī bàn jiě ， biàn zì fēng wéi “ tiān xià dì yī ” ， shì zú jiàn qí bù zì liàng ér yǐ ． The most ridiculous person in the world is the “know all” who picks up a smattering of hearsay knowledge and proclaims themselves “the world's Number One authority”; this merely shows that they have not taken a proper measure of themselves.
Don't overestimate your ability! How can you move this chair on your own?
Examples (Wiktionary)
Mandarin
世上最可笑的是那些“知识里手”，有了道听涂说的一知半解，便自封为“天下第一”，适足见其不自量而已。
世上最可笑的是那些“知識裏手”，有了道聽塗説的一知半解，便自封為“天下第一”，適足見其不自量而已。
shì shàng zuì kě xiào de shì nà xiē “ zhī shi lǐ shǒu ” ， yǒu le dào tīng tú shuō de yī zhī bàn jiě ， biàn zì fēng wéi “ tiān xià dì yī ” ， shì zú jiàn qí bù zì liàng ér yǐ ．
The most ridiculous person in the world is the “know all” who picks up a smattering of hearsay knowledge and proclaims themselves “the world's Number One authority”; this merely shows that they have not taken a proper measure of themselves.