not know (one's) own strength

(redirected from didn't know his own strength)

not know (one's) own strength

To underestimate how much force one is able to apply or exert in some physical activity. A: "Hey, you're pushing the car too fast! I just need to get it off the road, not down into the ditch!" B: "Oops, sorry. Guess I don't know my own strength!" You need to be more careful with that equipment. You don't know your own strength!
See also: know, not, own, strength
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

not know one's own strength

not to realize how destructive or harmful one's strength can be. I didn't mean to hurt you. I guess I don't know my own strength. He might break the door down by accident. He doesn't know his own strength and could end up pushing too hard against the door.
See also: know, not, own, strength
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.
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References in periodicals archive ?
Hallinan said Mirkarimi was always a "real efficient, businesslike guy"--but said he didn't know his own strength. "He's really strong, you know," Hallinan said, telling the Chronicle how during a celebration Mirkarimi "picked me up by the armpits.
Another meeting underlined that the Cannonball Kid simply didn't know his own strength.
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