What Does 10-4 Mean?

by Alex Questly

If you’ve ever watched a movie or TV show featuring truckers, police officers, or CB radio users, you’ve probably heard the phrase “10-4.” But what does it actually mean? Let’s break it down!


The Quick Answer

“10-4” is a radio communication code that means “message received” or “understood.” It’s a way to confirm that the person on the other end has heard and comprehended the message.


Origins of 10-4

The term comes from the Ten-Code, a system of radio codes developed in the 1930s by Charles Hopper, a communications director for the Illinois State Police. The Ten-Code was created to standardize and simplify radio communication, especially in noisy environments or when time was critical.

Each “10-” code represents a specific message. For example:

  • 10-4: Message received/understood.
  • 10-20: What’s your location?
  • 10-7: Out of service.

Who Uses 10-4?

While it originated in law enforcement, the phrase “10-4” has become widely used by various groups:

1. Law Enforcement

Police officers often use “10-4” to confirm they’ve received instructions or important updates over the radio.

2. Truckers

Truck drivers have adopted the phrase as part of their CB radio slang. It’s commonly used to confirm messages while communicating on the road.

3. Pop Culture

Thanks to its catchy and memorable nature, “10-4” has made its way into movies, TV shows, and general slang. It’s often used humorously or casually to mean, “Got it!”


How to Use 10-4 in Everyday Conversation

Though originally intended for professional communication, “10-4” can also be used informally in day-to-day life. Here are a few examples:

  • Confirming plans:
    “We’ll meet at the coffee shop at 3 PM.”
    “10-4!”
  • Acknowledging instructions:
    “Don’t forget to lock the door before you leave.”
    “10-4, got it!”
  • Showing agreement:
    “Are we all set to go?”
    “10-4, let’s do it!”

Other Common Ten-Codes

Here’s a quick look at some popular Ten-Codes you might hear:

CodeMeaning
10-1Unable to copy (poor signal)
10-7Out of service
10-9Repeat the message
10-20Location
10-33Emergency traffic only

Note: Different agencies may have variations in how these codes are used.


Why Did 10-4 Become So Popular?

There’s something undeniably catchy about “10-4.” Its popularity grew thanks to its simplicity, versatility, and frequent appearances in pop culture. It became a trademark phrase in:

  • Movies: Think Smokey and the Bandit and Convoy, which featured trucker culture prominently.
  • CB Radio Craze: In the 1970s, CB radios became a widespread hobby, and “10-4” was a go-to phrase.
  • Casual Speech: The phrase made its way into everyday language as a fun, easy way to say, “Understood.”

Fun Facts About 10-4

  1. National 10-4 Day: October 4th (10/4) is celebrated by truckers and radio enthusiasts as a fun nod to the phrase.
  2. NASA Use: Even astronauts use simplified radio codes, though “10-4” isn’t standard in space communication.
  3. Universal Appeal: While it originated in the U.S., “10-4” is understood worldwide, thanks to movies, music, and trucking culture.

Frequently Asked Questions

1. Is “10-4” still used today?

Yes! While modern technology has replaced radio communication in many professions, “10-4” is still commonly used by truckers, hobbyists, and even in casual speech.

2. Can “10-4” mean something else?

Its primary meaning is “message received,” but in informal contexts, it can also imply agreement, acknowledgment, or readiness.

3. Are there similar phrases in other languages?

Yes! For example, in French, “compris” (understood) might be used in a similar way. However, “10-4” is uniquely tied to English and CB radio culture.


Wrapping It Up: What Does 10-4 Mean?

“10-4” is more than just a radio code—it’s a universal way to say “message received” with flair. Whether you’re using it on the road, in a conversation, or just for fun, this iconic phrase has cemented its place in pop culture and communication history.

Got more curious phrases you’d like decoded? Let us know, and we’ll break it down, 10-4! 🚛📻

What Does “Roger That” Mean?

If you’ve heard the phrase “Roger that” alongside terms like “10-4,” you might wonder how they’re related. Both are common in radio communication, but they have distinct meanings and histories. Let’s break it down and connect it to our discussion of “10-4.”


The Quick Answer

“Roger that” means “I understand” or “I’ve received your message.” It’s a way of confirming that the speaker has heard and understood the transmitted message, similar to “10-4.”


The Origins of “Roger That”

The phrase comes from early military and aviation radio communication. Back in the day, voice clarity over radios wasn’t great, so the phonetic alphabet was used to spell out letters. The letter R, standing for Received, was communicated as “Roger” to ensure clarity.

  • “Roger” = Received
  • The addition of “that” emphasizes understanding.

Even though the phonetic alphabet was updated (and “Romeo” now represents the letter R), “Roger” stuck around as a classic acknowledgment term.


“Roger That” vs. “10-4”

While both phrases confirm receipt of a message, they are used in slightly different contexts:

PhraseMeaningContext
10-4Message received/understoodPrimarily used in law enforcement, trucking, and CB radio.
Roger ThatMessage received/understoodCommon in aviation, military, and general radio communication.

How Is “Roger That” Used Today?

Just like “10-4,” “Roger that” has moved beyond its technical origins and is now widely used in casual conversations. Examples include:

  • Acknowledging instructions:
    “Don’t forget to pick up the groceries on your way home.”
    “Roger that!”
  • Agreeing to plans:
    “We’ll meet at 7 PM.”
    “Roger that.”
  • In Pop Culture:
    The phrase is often heard in movies, TV shows, and video games, especially those involving military or aviation themes (e.g., Top Gun, Call of Duty).

Fun Facts About “Roger That”

  1. NASA Use: Astronauts use “Roger” during space missions to confirm they’ve received communications from mission control.
  2. “Over and Out” Confusion: “Roger” is often paired with “Over” (indicating you’re done speaking and waiting for a reply) but not with “Out” (which means the conversation is over). Saying “Roger, over and out” is technically incorrect!
  3. Global Appeal: While the phrase originated in English, it’s understood globally due to its heavy use in aviation and media.

Frequently Asked Questions

1. Is “Roger that” still used officially?

Yes, especially in aviation and military communications, where clarity and brevity are essential.

2. Can “Roger that” and “10-4” be used interchangeably?

In casual speech, yes. But in professional contexts, the choice depends on the industry—“10-4” is more common in law enforcement and trucking, while “Roger that” is favored in aviation and military.

3. What’s the origin of “Over”?

“Over” is a radio term meaning “I’m done speaking, and it’s your turn to reply.” It helps prevent overlap in two-way communication.


Tying It All Together: 10-4 and Roger That

Both “10-4” and “Roger that” are iconic ways to confirm receipt of a message. While they come from different traditions—one rooted in CB radio culture, the other in military and aviation—they serve the same purpose: making communication clear and efficient.

So, what’s your favorite radio phrase? Let us know in the comments—Roger that! 📻✈️

Alex Trivia
Alex Questly

Hi, I’m Alex—your trivia-obsessed, fact-hoarding host of this little corner of the internet. Picture me in my tiny home office, walls lined with shelves buckling under the weight of old trivia books, science magazines, and a stack of half-filled notebooks. My desk is a chaotic mess—a chipped coffee mug holding an army of pens, my laptop precariously perched atop an outdated encyclopedia, and post-it notes with scribbled reminders stuck to everything in sight (including, somehow, the cat). Welcome to the madness!

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