What does LMK mean?
LMK means “let me know,” a casual request for someone to reply with information, share a decision, or update you when something changes.
Also written: lmk · let me know
The meaning
LMK asks another person to tell you something. It can introduce a question about plans, invite an opinion, or ask for an update once information becomes available. In a group chat, “lmk if you're coming” requests a decision; it does not confirm attendance. The abbreviation takes the place of the full phrase inside a sentence, and lowercase lmk carries the same basic meaning as uppercase LMK.
What’s the tone?
Usually casual and neutral, LMK can also sound friendly or accommodating. A bare “LMK” gives little emotional context and may feel abrupt. Add a clear question, a polite phrase, or a deadline when the recipient needs more guidance.
When and how to use it
Use LMK in texts, direct messages, and informal chats to ask for a reply. Say what you need to know: availability, a choice, feedback, or confirmation that something arrived. If the timing matters, include a specific deadline rather than expecting the abbreviation to communicate urgency. Spell out “let me know” in formal correspondence or whenever the reader may be unfamiliar with texting shorthand.
In a conversation
Original examples to illustrate the expression.
I'm booking a table for Friday. Lmk by noon if you want a seat.
Count me in—thanks for checking.
The draft invitation is in the shared folder. Lmk if the date is hard to read.
The date looks clear. Could we make the address bigger?
Easy to misread
LMK requests a response; it is not an answer meaning yes, no, or “I know.” It also does not specify how quickly someone must reply. The following words supply the details, so “lmk when you arrive” and “lmk whether you're coming” ask for different information.
A little context
LMK belongs to the shorthand used in electronic communication. Collins records its texting and social-media meaning, while NetLingo lists it across chat, messaging, and other online writing. Grammarly's guide also documents its use in casual work communication. These references support an established abbreviation, but do not identify a verified inventor or exact first-use date.
Sources & further reading
These sources support the explanation. The dialogue above is original.
- LMK definition and meaning | Collins English DictionaryCollins English Dictionary · Checked Oct 30, 2026
Defines LMK as let me know and labels its use in messaging and social media.
- What Does Lmk Mean?Grammarly · Checked Oct 30, 2026
Explains LMK as a request for information or a reply and recommends spelling it out for formal communication or unfamiliar readers.
- LMKNetLingo · Checked Oct 30, 2026
Records let me know as online and text-message shorthand, including use in chat and instant messaging.
Prepared with AI assistance and automated quality checks. Meanings can vary by context. Read our editorial policy.