LMK Meaning: "Let Me Know" in Texts and Work Chat

LMK means "let me know." You use it to ask someone to tell you something later, such as a decision, an update or their opinion: "lmk if you want to come Saturday."

It is one of the most useful texting abbreviations because it shows up everywhere: in friends' group chats, in family texts, and constantly in workplace messaging tools. It is polite but very casual, so it pays to know when it sounds friendly, when it might read as pushy, and when "please let me know" works better.

Quick answer: LMK = "let me know." It asks for an answer or update: "lmk when you're home," "lmk what you think." It's fine in texts and most internal work chat. In formal emails write "Please let me know." Reply by answering or saying when you'll get back to them.

On this page

1. What LMK means
2. Where LMK came from
3. LMK and its family of abbreviations
4. LMK in everyday texting
5. LMK in work chat
6. The grammar behind LMK
7. More example sentences
8. How to reply to LMK
9. US vs UK vs Australia
10. When not to use it
11. A memory trick
12. Practice quiz: what does this message mean?
13. The takeaway

What LMK means

LMK is an initialism of let me know. It is always a request. The writer is waiting on you for something:

• A decision: "lmk if you want the spare ticket."
• An update: "lmk when you land."
• An opinion: "lmk what you think of the logo."
• A preference: "lmk which day works best."
• A problem, if there is one: "lmk if you need anything."

Pronunciation is simple: people say "let me know." Reading out the letters, "el-em-KAY," is rare but you may hear it jokingly.

"Let me know" is softer than it looks

Grammatically, "let me know" is an imperative, an instruction. In practice it is one of the gentlest ways to ask for something in English, because it frames the request around the speaker's need ("I'd like to know") rather than ordering the other person to act. That is why it works in so many settings, from a casual text to a polite email.

LMK keeps that softness, but because it is so short, the surrounding words matter. "lmk" alone can feel bare; "no rush, lmk when you can" feels relaxed.

Where LMK came from

LMK came out of the instant messaging and texting culture of the late 1990s and 2000s, when abbreviations such as BRB, BTW and TTYL became standard online. As with most of these, there is no recorded first use. "Let me know" is such a frequent phrase at the end of messages that a shortcut was almost inevitable.

What is notable about LMK is how well it crossed into professional life. As workplaces adopted chat tools for internal communication, many abbreviations stayed firmly social, but LMK, along with FYI and BTW, became part of everyday office messaging. It is now one of the abbreviations you are most likely to see from a manager or colleague.

LMK and its family of abbreviations

"I'll let you know," often written "ill lyk" or "will lyk," is the natural mirror of LMK: someone asks you to let them know, and you promise that you will. For the social version of "get in touch," see our guide to HMU.

LMK in everyday texting

Among friends and family, LMK is used constantly, and the tone is nearly always friendly.

Asha: going to the beach tomorrow if the weather holds, lmk if you want to come Sophie: yesss count me in

Dad: Lmk when you get to Leeds safely Ella: will do!

Mason: making a coffee run, lmk your order Ivy: oat flat white pls

Grace: I've got two spare tickets for the Ed Sheeran gig, lmk asap if you want them Liam: YES. how much

Aunt Jo: Lmk if you need anything for the new baby Harper: thank you, we're fine for now, will lyk!

Making LMK sound friendlier

These small additions remove any sense of pressure:

• "No rush, lmk when you can."
• "Lmk either way, totally fine if not."
• "Lmk if that works, happy to change it."
• "Lmk what you'd prefer!"

Phrases like "either way" and "totally fine if not" are particularly useful when inviting someone, because they make it easy to say no.

LMK in work chat

This is where LMK gets interesting. It is very common in internal messages, and it is usually fine, but it can come across differently depending on who sends it and how.

When it works well

Between peers, LMK is efficient and neutral:

Tom: Shared the Q3 draft in the folder, lmk if anything looks off Priya: Will take a look this afternoon

Rachel: Lmk if you want me to join the client call Josh: That'd be great, it's at 2

When it can feel pushy

From a manager, repeated or with no context, "lmk" can sound like pressure:

Manager: lmk Manager (an hour later): lmk?

A clearer version gives the reason and the deadline:

Manager: Could you let me know by 4pm whether the Melbourne figures are final? I need them for the board pack.

The second message is longer but kinder. The recipient knows what is needed, by when, and why.

Adding a deadline

One of the most common problems with LMK at work is that it has no time attached. "Lmk" could mean in five minutes or next week. If timing matters, say so: "lmk by Thursday," "lmk before EOD," or "lmk by noon so I can book the room." Our guide to other ways to say "as soon as possible" has polite ways to express urgency.

The grammar behind LMK

Because LMK is a shortened imperative ("let me know"), it behaves like the full phrase in a sentence. That means the words you put after it follow ordinary grammar rules, and getting them right makes your message clearer.

What can follow LMK

The difference between "lmk when" and "lmk if" matters more than people expect. "Lmk when the parcel arrives" assumes it will arrive and asks for a heads-up at that moment. "Lmk if the parcel arrives" leaves open the possibility that it won't, and might suggest you only need to hear back if it does. If you need a reply either way, say so: "lmk either way."

Capitals and punctuation

In casual texts, people write "lmk," "LMK" or "Lmk" interchangeably. All caps can look slightly more emphatic in a short message ("LMK!!"), while lowercase feels relaxed. At the start of a sentence in a work chat, "Lmk" with a capital L looks tidiest.

LMK is a request, not a question, so it does not need a question mark: "Lmk if you're free." Adding one ("lmk if you're free?") is common in texting and softens the tone, making it sound more like a gentle question than an instruction. Both are acceptable in informal writing.

Who is being asked

LMK always means "let me know." If you are passing on a request for someone else, the abbreviation doesn't fit. Write "Let Priya know" or "Can you let the team know?" in full, because "lmk" would wrongly point the reply back at you.

More example sentences

1. "Lmk if the train from Brighton is delayed."
2. "Lmk what time suits you for the call."
3. "Lmk if your mum needs a lift from the airport in Adelaide."
4. "Lmk which dates work for the team offsite."
5. "Lmk if you want the leftover lasagna."
6. "Lmk when the plumber arrives."
7. "Lmk if the invoice needs a purchase order number."
8. "Lmk how the interview in Seattle goes!"
9. "Lmk if you'd rather meet at the café on Queen Street."
10. "Lmk once the client signs off."
11. "Lmk what you think of the new menu."
12. "Lmk if the hotel in Glasgow has parking."
13. "Lmk if you hear anything about the results."
14. "Lmk which size you need and I'll order it."

How to reply to LMK

The person is waiting on you, so the most helpful reply does one of two things: gives them the answer, or tells them when they will get it.

If you know the answer: reply directly. "Yes, Saturday works," "The blue one," or "Landed safely!"

If you need time: acknowledge and give a timeframe. "Will check and lyk tonight," "Give me till Friday?" or "Good question, I'll find out."

If the answer is no: say so kindly and early. "Thanks for thinking of me, but I can't make it this time." Leaving someone waiting is usually worse than a polite no.

If they said "lmk if you need anything": you don't have to reply with a need. "Thank you, that's really kind" is enough.

One common mistake is replying "ok" or "will do" and then forgetting. If you promise to let someone know, set yourself a reminder. A follow-up such as "Sorry for the delay, the answer is yes!" is always better than silence.

US vs UK vs Australia

LMK is used and understood in the same way in all three countries, in both personal texts and work chat.

The spoken phrase is common everywhere too, though British and Australian speakers also use alternatives such as "give me a shout," "drop me a line" or "keep me posted." In Australia, "give me a bell" (meaning "call me") is a familiar informal phrase, and in the UK "give me a ring" is common. None of these has a widely used abbreviation, so LMK remains the go-to shortcut in all three places.

Workplace habits differ more by company than by country. Some teams in every country use abbreviations freely; others prefer full sentences. Follow the style of the people you work with.

When not to use it

In formal emails and client communication.

❌ "Lmk if you have questions about the proposal." ✅ "Please let me know if you have any questions about the proposal."

When the request is important or sensitive. A short acronym can make a serious question feel offhand.

❌ "lmk if you're still upset" ✅ "I'd really like to talk when you're ready. Let me know when suits you."

When you need a specific answer by a specific time.

❌ "lmk" ✅ "Could you let me know by Wednesday whether you can attend?"

When you have already asked. Sending "lmk?" repeatedly can feel like nagging. Wait a reasonable time, then follow up politely. Our guide to other ways to say "just checking in" helps with that.

With people unfamiliar with texting abbreviations. Some older relatives, or colleagues writing in a second language, may prefer the full phrase.

For a full list of professional alternatives, see other ways to say "please let me know".

Is LMK OK at work?

Usually yes, in internal chat, especially between people who already message casually. It is less suitable in emails, documents and anything external. A good test: if you would happily write "BTW" or "FYI" to this person, "LMK" is probably fine. If you would write "Dear," spell it out.

A memory trick

LMK is a little Light that says Message Kept waiting. Picture a light on your phone blinking until you answer. Whenever you see LMK, the other person is waiting, so either answer or tell them when you will.

Practice quiz: what does this message mean?

1. "Lmkwyt of my new haircut"
2. "lmk asap, the hotel only has one room left"
3. "Will lyk by Friday"
4. "No rush, lmk when you can"
5. "Lmk if you need a hand with the move"
6. "Could you lmk by EOD?"

Answers

1. "Let me know what you think." They want your opinion on the haircut.
2. "Let me know as soon as possible." It's urgent because the room might go.
3. "I'll let you know." It's the reply promising an answer by Friday.
4. "Let me know whenever." A relaxed request with no pressure.
5. "Tell me if you need help." An offer, not a demand.
6. "Let me know by the end of the day." A work request with a deadline.

The takeaway

LMK is a polite, efficient way to ask someone to get back to you, and it works almost anywhere casual, including most internal work chat. Make it friendlier with "no rush" or "either way," make it clearer with a deadline, and swap it for "please let me know" in formal writing. When someone sends you an LMK, the kindest reply is a quick answer or an honest timeframe.