LMK
An abbreviation for let me know.
“LMK when you're on the way.”
LMK asks for an update, decision, answer, or confirmation. It is casual but widely acceptable in everyday work messages too.
The abbreviation became common through texting, email, and instant messaging as a compact request for information.
let me know
The full phrase.
lmk asap
A request for a quick update.
lmk either way
A request for confirmation regardless of the decision.
What does LMK mean?
Let me know.
Is LMK professional?
It is fine in casual workplace communication, but writing it out is more formal.
Does LMK require a reply?
Usually yes, once the requested information is available.