What "K" and "M" Mean on Social Media

Have you ever noticed that English social media sites tend to have random letters of the alphabet floating around? For example, at the time of writing:

This tweet has 11.6 “K” likes.
CNN International’s Twitter has 12.5 “M” followers.

This Instagram page run by a member of our staff has 45.5 “K” followers:

You might have figured out that K is an abbreviation for “one thousand,” but why K? And what about M? Today, we’ll go into why these letters are used this way and whether these abbreviations can be used in English conversations as well.

K

The K in “10k followers” or “5K likes” comes from the metric system. It’s the same K as the ones in these abbreviations:

km (kilometer)
kg (kilogram)
kB (kilobyte)

But why does K mean 1000? Well, this goes back to ancient Greek. When French scientists were developing the metric system, they took “chilioi,” the Greek word for “thousand,” and turned it into the prefix “kilo-.”

In informal English, you’ll actually hear people just saying K, especially when they are talking about money. For example, here’s a video of a PhD student who shares that he makes “30K” a year:

M

M, which represents “million,” also comes from the metric system. It’s the same M that’s in units of measure such as:

MW (megawatt)
MB (megabyte)

You will see M used this way in news headlines, especially in financial news. After all, writing “m” or “M” saves a lot more space than writing out all the zeros or the full word (“million”).

“Canada Facebook fined $6.5m over 'false' privacy claims” (BBC)
“Japan ship operator to pay $9M over Mauritius oil spill” (Washington Post)

However, M is not as standard of an abbreviation as K. So you won’t hear people saying things like “The CEO of Facebook makes 23M a year.”

In addition, not all news agencies use “M” as an abbreviation for “million.” For example, the New York Times has stopped using this abbreviation since around 2010. One possible reason for this is that lowercase “m” also means “meter,” and this abbreviation is also often used in headlines, which could lead to confusion.

Anyways, since M isn’t a standard way to abbreviate “million,” don’t be surprised if you see other abbreviations, such as “mln” or “mn.”

In casual conversation, you’ll sometimes hear people abbreviate “million” to “mill.” For example, a person in the following video talks about how a business went from “0 to 100 mill” in revenue in 7 years:

Bonus: “Grand”

Did you know that there’s another casual way to say “a thousand dollars” in English?

This car cost me 30 grand.
The average cost of college tuition in the US is around 35 grand a year.

This expression is believed to have started with American mobs in the 1900s. These illegal groups were always moving around “grand” amounts of money and needed code words to refer to them. Funnily, their code word has since become a common slang expression around the English-speaking world!

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