50 Most Common Police Codes and What They Mean

There are close to a hundred ten-codes on the books, plus response codes, signals, and penal codes stacked on top. Almost none of that matters for following a scanner. Real police radio runs on a small core of codes that repeat endlessly, and once you know those, the rest is occasional detail you can look up. This is that core — the 50 codes you’ll actually hear, grouped by what they do and explained rather than just listed.

One rule before the list: police codes are not standardised. There is no national code book. Roughly 18,000 American agencies each set their own conventions, so the meanings below are the widely accepted versions, not universal law. Where a code is a known troublemaker, it’s flagged.

The Codes You’ll Hear in the First Five Minutes

Start here. These handful account for a startling share of all radio traffic, and learning them alone will let you follow the shape of most calls.

These are the bookends and connective tissue of every shift. An officer goes 10-8 at the start, takes a call, reports 10-97 on arrival, closes with 10-98, and eventually goes 10-7. Nearly every incident you follow is wrapped in this vocabulary. 10-4 is the most consistent code in American policing — it means “acknowledged” essentially everywhere — while 10-23 is one to watch, since some agencies use it for “stand by” rather than “on scene.”

Communication and Signal Quality

These manage the conversation itself: whether it’s coming through, whether to repeat, whether to wait.

10-1 is the single most dangerous code to assume you know. In the APCO-style list, it means a weak signal. In Chicago, 10-1 means an officer needs emergency help — the most urgent transmission on the channel. Same two digits, opposite ends of the scale. It’s the textbook illustration of why codes don’t travel, and our guide to Chicago police codes covers how differently CPD builds its system.

A note on 10-21: “call by telephone” often means a conversation is about to happen off the air, either because it’s sensitive or because it’s too complicated for radio. When you hear it, the interesting part of the story just left the channel.

Checks and Records

The bread and butter of traffic stops. These are the codes officers use to find out who and what they’re dealing with.

This cluster is the routine that precedes most stops. The officer calls the plate, dispatch runs it, and the answers come back. The rhythm is so regular that once you recognise it, you can follow a traffic stop from start to finish without decoding another word.

10-99 is the other big variation trap. In many agencies it means a record check came back wanted or stolen. In others it means an emergency, and in Chicago it means an acknowledgment from a one-officer unit. Three completely different meanings for the same code.

Incidents and Crimes

What’s actually happening. These describe the call itself.

Three of these deserve extra attention. 10-32 (person with a gun) changes the entire tone of a response — backup gets staged, officers slow down and think about cover. 10-33 clears the channel for an emergency, so when you hear it, everything else stops and the important thing is about to happen. And 10-50 is a genuine hazard: in Texas it’s a traffic accident, often with a severity suffix (10-50F for fatal, 10-50I for injury, 10-50PD for property damage only), but in parts of Louisiana 10-50 means officer down. That’s not a trivia point — it’s the kind of mismatch that costs seconds in a mutual-aid situation.

Status and Movement

Where officers are and what they’re doing.

10-42 is worth knowing for a reason beyond its plain meaning. It marks the end of a shift — routine, administrative, unremarkable. But it’s also the code used ceremonially in the “final call” at police funerals, when a dispatcher reads a fallen officer’s name over the radio and, receiving no answer, clears them from service for the last time. The ordinary sign-off becomes the profession’s most solemn goodbye precisely because it’s so ordinary the rest of the time.

The Response Codes (Not 10-Codes)

This is where people get confused. The response codes are a separate family — they tell officers how fast to get somewhere, not what’s happening.

Code 3 and Code 4 are the rhythm of every serious call: units run in hot under Code 3, handle it, and someone calls Code 4 to release the rest. If you learn to hear that arc, you can follow an incident from emergency to resolution without understanding anything in between.

Code 4 is not an emergency — it’s the opposite, the all-clear, and people reliably get this backwards because it has a number in it. And Code 7 is the most down-to-earth code in policing: an officer going to lunch. It’s also a quiet barometer of how busy the streets are. When Code 7 requests start flowing, things have calmed down.

These response codes came out of California and spread west and beyond. California stacks even more on top — 11-codes for traffic specifics, and penal code numbers like 187 and 211 spoken aloud to name crimes. Our US police code category lays out how these families relate.

The Ones That Change Meaning — A Cheat Sheet

If you take one thing from this list, take this table. These are the codes most likely to mislead you.

Every one of these pairs is a real, live discrepancy between real agencies. This is why federal guidance since the multi-agency communication failures during Hurricane Katrina has pushed departments toward plain language for anything crossing jurisdictional lines — when responders from three agencies converge on a scene, “officer down” needs to mean officer down to all of them. Our US 10-codes guide traces how the system fragmented this way.

How to Actually Learn These

Don’t memorise the list. Fifty codes is too many to hold cold, and you don’t need to.

Learn the seven from the first section — 10-4, 10-8, 10-7, 10-20, 10-97, 10-98, and the response Codes 3 and 4. That’s nine items, and it’s enough to follow the structure of nearly any call: someone’s available, they’re sent somewhere at some urgency, they arrive, it resolves. The specific incident code in the middle is the one thing you look up, and you’ll look up the same dozen over and over until they stick.

Then anchor everything to the agency. Before you trust any meaning, know who’s talking — a city PD, a county sheriff, and a state agency on the same scanner may not use the same list. That single habit prevents most misunderstandings.

Finally, listen for what surrounds a code. A 10-32 paired with a backup request and a 10-33 to clear the air tells you everything about how seriously it’s being taken, regardless of whether you caught the exact number. Context does a lot of the work.

The codes exist because in 1937 police radios needed a spare syllable to spin up to full power, and because airtime was scarce. Nearly a century later, the technology has changed completely, and the codes have stayed — smaller, patchier, sharing the channel with plain English, but still there. Learn the core fifty, and you can read most of what’s left. For the fuller catalogue across states and countries, the master police code lists page is the place to go next.

Using Police Code to Explore Further

Police Code is a global police code explorer built for exactly the problem this article describes: a code means one thing here and another thing there, and a generic list won’t tell you which. You can search one organised database that compares usage across departments and countries, separates the code families that get conflated, and shows the references behind each entry. It’s free to browse and built for scanner listeners, journalists, writers, and anyone learning to follow a feed.