Police 10 codes are the numbered radio signals American officers and dispatchers use to say common things quickly: “message received,” “what’s your location,” “traffic accident,” “officer needs help.” Almost everyone knows 10-4, and plenty of people know 10-20, but the full list runs from 10-0 into the hundreds, and the meaning of a given number depends heavily on who is talking. This guide walks through the standard list group by group, explains what each code tells you in practice, and flags the ones that mean something different in New York, Chicago, Texas, and elsewhere.
One caveat comes first, because it shapes how to use everything below. There is no national code book. Each of the roughly 18,000 law enforcement agencies in the United States chooses its own conventions, so what follows is the widely used APCO-style baseline, not a rule. Where a major department disagrees with the baseline, the difference is noted.
What Police 10 Codes Are
A ten-code is the word “ten” followed by a number. Each one stands in for a phrase that would otherwise take several seconds to say, which matters on a radio channel shared by a whole shift of officers. Instead of “I’ve arrived at the location and I’m getting out of the car,” an officer says a single code, and dispatch logs it.
The codes cover a few broad jobs. Some manage the conversation itself (can you hear me, say again, stand by). Some track where an officer is and what they’re doing (in service, out of service, en route, arrived). Some name the kind of call (a prowler, a disturbance, a crash). And a smaller group handles records checks, prisoners, alarms, and administrative messages. Grouping them by job makes the list far easier to learn than memorising 10-0 through 10-99 in order.
Where Police 10 Codes Came From
The system was built in the late 1930s by Charles Hopper, a communications director with the Illinois State Police, working with what became APCO, the Association of Public-Safety Communications Officials. Early police radios had a real technical flaw: the first fraction of a second of a transmission was often clipped while the equipment reached full power. Putting the word “ten” in front of every code gave the radio a throwaway syllable to burn, so the number that followed arrived intact.
The codes spread across the country, and television and citizens-band radio later pushed a few of them into everyday speech. Our guide to why police say 10-4 tells that story in full, and the broader overview of police radio 10-codes in the United States covers how the list developed and where it stands today.
Radio and Communication Codes
These manage the conversation. They’re short, they come up constantly, and most of them mean roughly the same thing everywhere.
| Code | Standard meaning | What it tells you |
|---|---|---|
| 10-0 | Use caution | A warning to be careful, often before a dangerous call |
| 10-1 | Signal weak | The listener can’t hear clearly; repeat or change position |
| 10-2 | Signal good | The transmission is coming through fine |
| 10-3 | Stop transmitting | Clear the channel for something more urgent |
| 10-4 | Acknowledged | Message received and understood |
| 10-5 | Relay message | Pass this along to another unit or agency |
| 10-6 | Busy, stand by | Not available to talk unless it’s urgent |
| 10-9 | Repeat | Say that again |
| 10-12 | Stand by | Wait; often used when others are present |
| 10-21 | Call by telephone | The conversation is moving off the air |
| 10-22 | Disregard | Cancel the last assignment or message |
| 10-36 | Correct time | Asking for or giving the time |
| 10-43 | Information | A request for or note of information |
10-4 is the most consistent code in American policing. It means “acknowledged” nearly everywhere, which is a big part of why it escaped into ordinary speech. 10-21 is a quiet signal worth noticing: when an officer is told to call in by phone, the next part of the conversation is either sensitive or too involved for the radio.
Status and Movement Codes
These track an officer through a shift. If you follow a scanner, they form the skeleton of nearly every call: available, sent somewhere, arrived, finished.
| Code | Standard meaning | What it tells you |
|---|---|---|
| 10-7 | Out of service | Unavailable for calls |
| 10-8 | In service | Available for assignment |
| 10-17 | Meet complainant | Go and speak with the person who called |
| 10-18 | Urgent | Complete the assignment quickly |
| 10-19 | Return to station | Head back to the station or office |
| 10-20 | Location | “What’s your 10-20?” means “where are you?” |
| 10-23 | Arrived at scene | On location (some agencies use it for “stand by”) |
| 10-24 | Assignment complete | Finished with the call |
| 10-41 | Beginning tour of duty | Starting a shift |
| 10-42 | Ending tour of duty | Ending a shift |
| 10-44 | Request permission to leave patrol | Asking to step away from the assigned area |
| 10-60 | Squad in vicinity | Another unit is nearby |
| 10-61 | Personnel in area | Others are present at or near the location |
| 10-76 | En route | On the way to the call |
| 10-77 | Estimated time of arrival | How long until arrival |
| 10-86 | Operator on duty | Dispatcher or operator is working |
10-8 and 10-7 are the bookends of a working day, and 10-20 is the code that crossed into slang. 10-42 has a second life as well: it’s also the number used in the solemn “final call” tradition for a fallen officer, which we cover in what 10-42 means as the end-of-watch code.
Two entries in this group have shifted in practice. In the original APCO list, 10-97 was a signal test and 10-98 was a jail break. Most agencies repurposed them over the years, so on many channels 10-97 now means “arrived on scene” and 10-98 means “assignment complete.” If you read an older list and see something different, that’s why.
Records and Checks
This small cluster is the routine behind most traffic stops. The officer calls in a plate or a name, and dispatch runs it.
| Code | Standard meaning | What it tells you |
|---|---|---|
| 10-25 | Report in person | Meet face to face rather than by radio |
| 10-26 | Detaining suspect | Someone is being held while a check is run |
| 10-27 | Driver’s licence check | Running a licence |
| 10-28 | Vehicle registration check | Running a plate |
| 10-29 | Check for wants or warrants | Looking for outstanding warrants |
| 10-99 | Records indicate wanted or stolen | The check came back with a hit |
Hearing 10-28 followed by 10-29 usually means a stop is underway and the officer is deciding how to proceed. 10-99 is the answer nobody wants to hear during a stop, though as we’ll see it’s also one of the codes most likely to mean something else in a different agency.
Incident and Crime Codes
These describe what’s actually happening. The group is where agencies disagree most, so treat these as the common versions and confirm locally.
| Code | Standard meaning | What it tells you |
|---|---|---|
| 10-14 | Prowler report | Someone suspicious is lurking at a property |
| 10-15 | Civil disturbance | A crowd or dispute is causing disorder |
| 10-16 | Domestic problem | A dispute inside a household |
| 10-30 | Danger or caution | Varies: unauthorised radio use in the original list |
| 10-31 | Crime in progress | Something is happening right now |
| 10-32 | Person with a gun | An armed individual is involved |
| 10-33 | Emergency | Clear the channel for emergency traffic |
| 10-34 | Riot | Large-scale disorder |
| 10-35 | Major crime alert | A serious crime has been reported |
| 10-37 | Suspicious vehicle | A car that warrants a look |
| 10-38 | Stopping suspicious vehicle | A traffic stop; the officer reads the plate |
| 10-39 | Urgent, use lights and siren | Respond with emergency equipment |
| 10-40 | Silent run | Respond without lights or siren |
| 10-80 | Pursuit in progress | A chase is underway |
| 10-89 | Bomb threat | A threat has been reported |
| 10-90 | Bank alarm | An alarm at a financial institution |
| 10-96 | Mental subject | A person in a mental health crisis |
10-32 changes the tone of a call more than almost any other code. It tells everyone listening that a firearm is involved, so backup gets staged and officers slow down. Our guide to what 10-32 means and why it varies by department explains how it’s used and where the meaning drifts. 10-33 is the other one to listen for: when it goes out, routine traffic stops so the emergency has the channel to itself.
Traffic and Roadway Codes
Because so much of policing happens on the road, this is the largest cluster in the list.
| Code | Standard meaning | What it tells you |
|---|---|---|
| 10-46 | Assist motorist | A stranded or stopped driver |
| 10-47 | Emergency road repair | A hazard needs urgent repair |
| 10-48 | Traffic signal repair | A signal is malfunctioning |
| 10-49 | Traffic light out | A signal is dark |
| 10-50 | Traffic accident | A crash; severity is often added as a suffix |
| 10-51 | Wrecker needed | A tow truck is required |
| 10-53 | Road blocked | The roadway is obstructed |
| 10-54 | Livestock on highway | Animals on the road |
| 10-55 | Intoxicated driver | A suspected impaired driver |
| 10-56 | Intoxicated pedestrian | A suspected impaired person on foot |
| 10-57 | Hit and run | A driver left the scene |
| 10-58 | Direct traffic | An officer is needed to control traffic |
| 10-59 | Convoy or escort | Accompanying a vehicle or group |
| 10-81 | Breathalyzer report | A breath test result |
| 10-92 | Improperly parked vehicle | A parking complaint |
| 10-93 | Blockade | A deliberate roadblock |
| 10-94 | Drag racing | Street racing |
10-50 deserves its own note. In Texas it’s a traffic accident, and officers attach a letter to show severity: 10-50F for a fatal crash, 10-50I for injuries, 10-50PD for property damage only. That single letter decides whether the response is a tow truck and a report or ambulances and a supervisor. Our Texas 10-codes guide lists the full set DPS and many Texas agencies use.
Fire, Medical, and Other Codes
A last handful of codes cover emergencies that aren’t strictly police business, plus a few that don’t fit elsewhere.
| Code | Standard meaning | What it tells you |
|---|---|---|
| 10-45 | Animal carcass | A dead animal to be removed |
| 10-52 | Ambulance needed | Medical response required |
| 10-70 | Fire alarm | An alarm has gone off |
| 10-71 | Advise nature of fire | Asking what kind of fire |
| 10-72 | Report progress on fire | An update on the fire |
| 10-73 | Smoke report | Smoke has been observed |
| 10-79 | Notify coroner | A death requires the coroner |
| 10-91 | Pick up prisoner or subject | Collect someone in custody |
| 10-95 | Prisoner in custody | Someone is being held |
The remaining codes in the 10-62 to 10-69 range are administrative, covering message delivery and cancellation. They were built for the era of teletype and net messages and are rarely heard on a modern channel.
The Codes That Mean Different Things
If you take one section from this guide, take this one. The codes with the highest stakes are often the least standardised, and a few of the differences are stark.
10-1. The baseline says “signal weak,” which is routine radio housekeeping. In Chicago, 10-1 is the call that an officer needs emergency help, the most urgent transmission the department makes. Our guide to Chicago police codes explains how CPD stripped its list down to a handful of codes and made this one exception load-bearing.
10-13. In the standard reference list, it’s a request for weather and road conditions. In the NYPD, 10-13 means “assist police officer,” an emergency that pulls units from across the surrounding precincts. The NYPD also builds its crime codes in pairs, a “past” version and an “in progress” version ten numbers apart, which you can see in our NYPD codes guide.
10-50. A traffic accident in Texas and most places, but in parts of Louisiana it means officer down. That kind of mismatch is exactly what causes trouble when agencies from different areas respond to the same hurricane or manhunt.
10-99. Many agencies use it for “records indicate wanted or stolen.” Others use it as an emergency, and Chicago uses it to acknowledge a message from a one-officer car, with 10-4 reserved for two-officer units.
10-10. Depending on the agency it can mean off duty, out of service, negative, or a fight in progress. It’s a good example of a code you shouldn’t try to translate without knowing who sent it.
10-97 and 10-98. As noted above, the original APCO meanings (signal test and jail break) were replaced in everyday use by “arrived” and “assignment complete.”
The practical rule is simple. Before you trust any meaning, identify the agency broadcasting. A city police department, a county sheriff, and a state patrol sharing the same scanner may not use the same list.
What 10-Codes Don’t Cover
Ten-codes are one family among several, and a ten-code list on its own won’t decode everything you hear.
Response codes are separate. Code 1 through Code 7 tell officers how fast to respond and what their status is, from routine through emergency (Code 3, lights and siren) to all clear (Code 4) and meal break (Code 7). Our guide to emergency response codes in the United States covers the full set.
Eleven-codes are a parallel numbering system associated mainly with the California Highway Patrol, with a focus on collisions and roadway incidents. See police radio 11-codes for the list.
Signals replace ten-codes across much of the Southeast. Florida agencies describe incidents with Signal 1 through Signal 100, and a ten-code sheet is of limited use on a Florida channel. Our Florida signals guide explains how that system works.
Penal codes are spoken aloud in California, where officers name a crime by citing the statute number. Our California penal codes guide lists the common ones, and the LAPD codes guide shows how a single Los Angeles transmission can stack a response code, a penal code, and a ten-code together. For a side-by-side comparison of these families, see 10-codes vs 11-codes vs penal codes.
Do Police Still Use 10-Codes?
Yes, but less than they used to, and unevenly. The reason is the same inconsistency this guide keeps returning to. Within a single department, codes are fast and unambiguous. Across departments, they can be dangerous, because a code that means “officer in trouble” to one agency may mean something harmless to another.
That problem became impossible to ignore after Hurricane Katrina in 2005, when responders from different jurisdictions struggled to understand each other’s radio traffic. Federal guidance, including the national incident management framework, has since pushed agencies toward plain language for anything involving more than one agency.
The result is a hybrid. Large departments often use plain English for complex or multi-agency incidents and keep codes for routine internal traffic. Small rural departments that rarely work outside their own county have often kept the full list, because everyone on their channel shares the same book. Some departments have dropped ten-codes almost entirely. Neither approach is wrong; they’re reasonable answers to different situations.
How to Learn Police 10 Codes Without Memorising Them All
Trying to hold the full list in your head is a poor use of time. The working vocabulary on a real channel is much smaller, roughly a dozen codes that repeat all day: 10-4, 10-7, 10-8, 10-20, 10-23, 10-28, 10-29, 10-38, 10-50, 10-97, 10-98, and the response codes. Learn those first, and treat the rest as reference you’ll look up a handful of times a year.
Pair that with the one piece of police radio that doesn’t change between agencies: the phonetic alphabet, which officers use to spell plates and names. Our guide to the police phonetic alphabet covers it.
When a code surprises you, sort it into its family first. Is it a ten-code, an eleven-code, a signal, a response code, or a penal code? Once you know the family, the number is much easier to place. Then check the agency, because the same number can carry a different meaning one county over.
Using Police Code to Explore Further
Police Code is a global police code explorer built around the problem this guide describes: there is no single master list, so the reliable way to know what a code means is to check it against the agency and place actually using it. If you want a quick reference to keep beside a scanner, the printable police 10-codes PDF is a good starting point, and the main police code lists page collects the full set of guides by state, department, and country. For the national picture, start with the United States police code overview. The platform is free to browse and built for scanner listeners, journalists, writers, dispatch trainees, and anyone who has heard a number crackle across a radio and wanted to know what it meant.