Law Enforcement 10 Codes: Complete Police Radio Code List (10-1 to 10-100)

Law Enforcement 10 Codes: Complete Police Radio Code List (10-1 to 10-100)

Switch on any police scanner in America and within seconds you will hear it. A clipped voice says "ten-four," another voice answers "ten-twenty?" and a dispatcher cuts in with "ten-thirty-three." To outsiders it sounds like a secret language. To officers, firefighters, and EMS crews it is the fastest way to push a clear message through a crowded radio channel without burning airtime or tipping off everyone listening with a scanner app.

This page lists every law enforcement 10 code from 10-1 all the way to 10-100. We cover where the codes came from, why some departments still swear by them while the federal government wants them gone, how they vary from Florida to Texas to California, what "Code 4" actually means (hint: it is not a 10 code), and the basic radio habits every new academy cadet has to memorize before their first shift.

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What Are Law Enforcement 10 Codes?

10 codes — sometimes written as ten codes, ten-codes, or hyphenated "10-4" style — are a numeric shorthand system that police, fire, EMS, and some military radio operators use to transmit common phrases in two syllables instead of twenty. Saying "10-4" takes about half a second. Saying "I acknowledge your last transmission and will comply" takes four full seconds and chews up channel time that another officer might desperately need to call for backup. Multiply that across a hundred radio exchanges per shift and the savings become enormous.

The codes were invented in 1937 by Charles "Charlie" Hopper, communications director for the Illinois State Police. Early radio equipment had a small delay between when an operator keyed the microphone and when the carrier actually started transmitting, so the first syllable of each message was often clipped off and lost.

Hopper realized that prefixing every message with the digit "10" gave the radio time to come on-air, after which the second number — the meaningful one — would always come through clean. The system worked so well that the Association of Public-Safety Communications Officials (APCO) adopted a standardized list in 1940 and pushed it nationwide.

By the 1970s, CB radio popularity exploded the codes into pop culture. Truckers, hobbyists, and the movie Smokey and the Bandit made "10-4 good buddy" a household phrase. That same popularity is part of what eroded the codes' usefulness — once every civilian with a scanner could decode them, the privacy advantage disappeared.

Why Do Police Still Use 10 Codes?

Five reasons keep the system alive in thousands of departments. Speed is the obvious one — fewer syllables, less airtime. Clarity over bad radio matters too; numbers transmit cleaner than full sentences through static, wind noise, or a partially-keyed mic. Operational discretion still has some value: while every scanner buff knows 10-4, the difference between 10-15, 10-50P, and 10-50I is not common knowledge, and on a long pursuit those small ambiguities buy seconds.

The fourth reason is tradition and academy training. Officers who spent six months at the academy memorizing the local 10 code list have it burned into muscle memory. Switching a 30-year-veteran to plain English after retirement-eligible service tends to fail. The fifth reason is tactical brevity in stress — an officer who is being beaten on the ground can squeak out "33" or "86" when she cannot string together "officer needs help immediately at the corner of..." The shortest possible code is the one she can still transmit.

Why Departments Are Dropping 10 Codes

The 2005 Hurricane Katrina response exposed a fatal weakness in the system. Mutual-aid responders from Texas, Tennessee, and Michigan flooded into Louisiana to assist New Orleans PD. Their 10 codes did not match. A Texas officer's "10-50" meant a traffic accident; a Louisiana officer's "10-50" meant officer down. Misunderstandings cost time and almost cost lives. The Department of Homeland Security and FEMA responded with a directive recommending plain language for all multi-jurisdictional operations under the National Incident Management System (NIMS).

Since 2006, large agencies like the NYPD, the California Highway Patrol, and Florida's Miami-Dade Police Department have moved their primary radio traffic to plain English, retaining only a handful of legacy codes. Smaller rural sheriff's offices that rarely interact with outside agencies have mostly kept the full code list. The result is a hybrid landscape where the answer to "do cops still use 10 codes?" is genuinely "depends which cop."

The Complete APCO 10 Code List

Below is the full Association of Public-Safety Communications Officials standard list of 10 codes, from 10-1 through 10-100. Treat this as a reference, not a universal truth — your local department will have its own variations. New officers should always study the agency-issued radio code card before reporting to first shift.

Codes 10-1 through 10-30 (Communication and Status)

• 10-1 Receiving poorly / signal weak.
• 10-2 Receiving well / signal good.
• 10-3 Stop transmitting.
• 10-4 Acknowledged / OK / affirmative.
• 10-5 Relay message to another unit.
• 10-6 Busy, stand by unless urgent.
• 10-7 Out of service / unavailable.
• 10-8 In service / available for assignment.
• 10-9 Repeat / say again your last message.
• 10-10 Negative / no.
• 10-11 Dog case (animal complaint).
• 10-12 Stand by / officials with you (visitors in the car).
• 10-13 Weather and road conditions.
• 10-14 Suspicious person / report of prowler.
• 10-15 Prisoner in custody.
• 10-16 Pick up prisoner.
• 10-17 Pick up papers / documents.
• 10-18 Urgent / complete assignment quickly.
• 10-19 Return to station / headquarters.
• 10-20 Location ("what's your 20?").
• 10-21 Telephone (call by phone, not radio).
• 10-22 Disregard / cancel last.
• 10-23 Stand by / arrived on scene.
• 10-24 Assignment complete.
• 10-25 Meet officer at location.
• 10-26 Detaining subject, expedite.
• 10-27 Driver's license information request.
• 10-28 Vehicle registration / plate check.
• 10-29 Wanted / stolen check on subject or vehicle.
• 10-30 Unnecessary use of radio (warning to operator).

Codes 10-31 through 10-60 (Crimes, Traffic, and Field Activity)

• 10-31 Crime in progress.
• 10-32 Person with a firearm.
• 10-33 EMERGENCY — clear all traffic from channel.
• 10-34 Riot / civil disturbance.
• 10-35 Major crime alert.
• 10-36 Correct time of day.
• 10-37 Investigate suspicious vehicle.
• 10-38 Stopping suspicious vehicle (give location and plate).
• 10-39 Urgent — use lights and siren.
• 10-40 Silent run — no lights or siren.
• 10-41 Beginning tour of duty.
• 10-42 Ending tour of duty.
• 10-43 Information needed.
• 10-44 Permission to leave the patrol area.
• 10-45 Animal carcass on roadway.
• 10-46 Motorist assist needed.
• 10-47 Emergency road repair.
• 10-48 Traffic signal repair.
• 10-49 Traffic signal out at intersection.
• 10-50 Traffic accident — suffix F for fatal, I for injury, P for property only.
• 10-51 Wrecker / tow truck needed.
• 10-52 Ambulance / EMS needed.
• 10-53 Road blocked.
• 10-54 Livestock on highway.
• 10-55 Intoxicated driver / DUI.
• 10-56 Intoxicated pedestrian.
• 10-57 Hit and run accident.
• 10-58 Direct traffic at this location.
• 10-59 Convoy or escort needed.
• 10-60 Squad in vicinity.

Codes 10-61 through 10-100 (Administrative and Special)

• 10-61 Personnel in area.
• 10-62 Reply to message.
• 10-63 Prepare to make written copy.
• 10-64 Message for local delivery.
• 10-65 Net message assignment.
• 10-66 Message cancellation.
• 10-67 Clear for net message.
• 10-68 Dispatch information.
• 10-69 Message received.
• 10-70 Fire alarm / fire reported.
• 10-71 Advise nature of fire.
• 10-72 Report progress on fire.
• 10-73 Smoke report.
• 10-74 Negative (older usage; modern equivalent is 10-10).
• 10-75 In contact with subject.
• 10-76 En route to location.
• 10-77 Estimated time of arrival (ETA).
• 10-78 Need assistance.
• 10-79 Notify coroner.
• 10-80 Chase / pursuit in progress.
• 10-81 Reserved (varies widely by agency).
• 10-82 Reserve lodging for prisoner.
• 10-83 Work / direct traffic at school crossing.
• 10-84 If meeting, ETA.
• 10-85 Will be delayed / running late.
• 10-86 OFFICER NEEDS HELP — code red, all units respond.
• 10-87 Pickup of evidence or subject.
• 10-88 Present telephone number.
• 10-89 Bomb threat.
• 10-90 Bank alarm.
• 10-91 Pick up subject.
• 10-92 Vehicle parked illegally.
• 10-93 Blockade established.
• 10-94 Drag racing in progress.
• 10-95 Prisoner or subject in custody.
• 10-96 Mental subject / psychiatric subject.
• 10-97 Check signal / arrived at scene.
• 10-98 Prison or jail break / escape.
• 10-99 Records indicate wanted or stolen.
• 10-100 Restroom / bathroom break (slang, unofficial in most departments).

10 Codes by State: Major Variations

Although APCO published a national standard list in 1940, almost no agency adopted it exactly. Every state has its own quirks, and within states individual departments add or drop codes. Here is how some of the biggest jurisdictions handle the system.

California — 10 Codes Plus 11 Codes

The California Highway Patrol uses both 10 codes and an entirely separate set of 11 codes (for example, 11-99 means officer needs help, which is what most other states call 10-86). LAPD and most municipal California departments use a hybrid: a small list of 10 codes plus a separate numeric set called "penal code numbers" (e.g., 187 for homicide, 211 for armed robbery, 415 for disturbance, 5150 for psychiatric subject). California's reliance on penal codes alongside 10 codes makes its radio traffic some of the most code-dense in the country.

Texas — Hybrid System

Texas Department of Public Safety uses a moderate 10 code list with additional state-specific codes. The Texas 10 code list reduces some APCO codes and adds others for ranch-and-highway scenarios uncommon in urban areas (livestock on highway, abandoned vehicle on rural FM road, agricultural-equipment-related issues). Many Texas sheriffs' offices have moved closer to plain language since 2010, though smaller rural counties still use the full code list.

Florida — County-by-County

Florida has no unified statewide code list. Each county sheriff and municipal department maintains its own. The florida department of law enforcement (FDLE) state agents tend to use plain language across the state, while county deputies use traditional 10 codes. Mutual aid during hurricanes and major incidents has been a recurring problem — exactly the issue DHS flagged in 2006.

New York — Mostly Plain Language

The NYPD officially transitioned to plain English in the mid-2000s after the September 11 response demonstrated interoperability problems with FDNY and Port Authority radios. A few legacy 10 codes survive in NYPD communications (10-13 "officer needs assistance," 10-85 "need additional unit") but most traffic is conducted in plain words.

South Carolina — Active 10 Code Use

The south carolina law enforcement division (SLED) and most South Carolina county sheriff's offices retain a full 10 code list. South Carolina has not made the federal push to plain language as aggressively as Florida or California, and its rural-heavy radio traffic still leans on numeric codes.

What Does Code 4 Mean? (And Other Non-10 Codes)

One of the most common questions civilians ask about police radio is "what does Code 4 mean?" The answer is that Code 4 is not a 10 code at all. It belongs to a separate category called "Code-numbers" or "radio call codes," which sit alongside the 10 code system rather than replacing it.

The standard call codes most American agencies recognize are:

• Code 1 — Routine response, no urgency, obey all traffic laws.
• Code 2 — Urgent response, no lights or siren, drive slightly above normal speed.
• Code 3 — Emergency response, lights and siren, proceed with caution but get there fast.
• Code 4 — Situation under control, no further units needed, additional responders can disregard.
• Code 5 — Stakeout in progress, stay out of the area unless requested.
• Code 6 — Out of vehicle investigating, may need cover.
• Code 7 — Meal break (varies by department).

Code 4 is the most popular outside the 10 codes because it shows up in countless movies and TV shows. It is shouted across crime scenes to tell responding units to slow down and stand down once the primary unit confirms the threat is neutralized.

The Phonetic Alphabet — Used Regardless of 10 Codes

One thing that survives every department's communication style is the NATO phonetic alphabet — Alpha, Bravo, Charlie, Delta, Echo, Foxtrot, Golf, Hotel, India, Juliett, Kilo, Lima, Mike, November, Oscar, Papa, Quebec, Romeo, Sierra, Tango, Uniform, Victor, Whiskey, X-ray, Yankee, Zulu. Officers use it to spell license plates, addresses, surnames, and any letter that could be confused over radio (B vs P vs D, M vs N, F vs S). Whether your department uses 10 codes, plain English, or a hybrid, you will still hear "Tag is Tango-Romeo-Foxtrot-7-2-9."

Some older departments and military-trained officers still use the LAPD phonetic alphabet (Adam, Boy, Charles, David, Edward, Frank, George, Henry, Ida, John, King, Lincoln, Mary, Nora, Ocean, Paul, Queen, Robert, Sam, Tom, Union, Victor, William, X-ray, Young, Zebra), but NATO has become the default in 21st-century policing.

How 10 Codes Work on a Real Radio Channel

A typical radio exchange tells the story better than any explanation. Picture an officer on patrol, late afternoon, light traffic. Here is what an actual scanner feed might sound like:

"Adam-12, 10-8 from the station." (Adam-12 is in service and just left HQ.)

"10-4, Adam-12. Show 10-8." (Dispatch acknowledges and logs status.)

"Adam-12, 10-28 on plate 7-Sierra-Romeo-9-2-4." (Officer is running a plate she just observed.)

"Adam-12, 10-28 returns to white 2018 Toyota Camry, registered to Smith, John, 24 Main, valid." (Plate is clean.)

"10-4. 10-20 Eastbound Highway 101 at exit 12, 10-38 on traffic stop." (Officer giving location and announcing she is stopping the vehicle.)

"10-4, Adam-12. Stand by for backup."

(Two minutes later) "Adam-12, 10-27 on operator David, Mary, James, 1-2-3-4-5-6-7." (Running the DL.)

"Adam-12, 10-27 returns valid, no wants no warrants."

"10-4. Show me 10-98 in five." (Will clear the call shortly.)

The entire exchange takes less than two minutes and gives dispatch a complete record of the stop — start time, location, vehicle, driver, and end time — in case anything goes wrong. Now imagine that same exchange in plain language. It would take roughly twice as long and tie up the channel for other units. That is the case for keeping 10 codes alive.

Learning 10 Codes in the Academy

Every police academy in the country teaches 10 codes during the first month of training, regardless of whether the hiring agency uses them in daily operations. The reasoning is twofold: cadets may transfer agencies later, and many neighboring jurisdictions still broadcast in codes, so an officer working a mutual-aid call needs to understand the radio traffic around her.

At the law enforcement academy, cadets typically receive a laminated pocket-card listing the agency's official codes. They are expected to memorize the entire list, with a written exam in week two or three. The exam is usually multiple choice — "What does 10-86 indicate?" — and a failing score requires remediation. By graduation, cadets are radio-fluent enough to take dispatch traffic in real time during ride-alongs.

Beyond memorizing the list, academy instructors drill on radio etiquette — pausing before transmitting, holding the mic correctly, speaking at conversational speed (not faster), and not stepping on other transmissions. These habits matter as much as code knowledge. An officer who can recite all 100 codes but mumbles into the mic is still a liability on the channel.

For applicants still preparing to enter the academy, the entry exam itself usually does not test 10 codes (it tests reading comprehension, basic math, situational judgment, and writing). Review the standard law enforcement requirements and the law enforcement how to pass law enforcement exam guide to know what is actually tested before academy starts.

10 Codes for Civilians: Should You Learn Them?

Some civilians — journalists, neighborhood-watch volunteers, scanner hobbyists, attorneys, and family members of officers — learn 10 codes to follow local radio traffic. There is nothing illegal about it. Police scanner traffic on UHF and VHF unencrypted bands is public-domain communication, and millions of people listen via apps like Broadcastify or Scanner Radio.

If you want to learn for legitimate reasons, start with the top ten codes listed above and add others as you hear them. Most online code lists are accurate for APCO standard but miss local variants — listen to your specific local agency and build a personal list. Note that more departments are moving radio traffic to encrypted digital channels (P25 Phase 2, especially for tactical and detective work), so increasingly some of the most interesting traffic is no longer publicly audible regardless of code knowledge.

The Future of Police Radio Codes

The trend is unmistakable: large agencies are moving away from 10 codes toward plain language. DHS and FEMA continue to push the change. Newer officers, raised on text messaging and natural-language voice assistants, find plain English more intuitive. Within twenty years, 10 codes will probably survive only in small rural sheriff's offices and as a tradition taught in academy.

That said, certain codes are too useful to die. "10-4" is now part of American English. "What's your 20?" appears in casual conversation. "Code 4" shows up in every cop show. Even if departments officially switch to plain language, these codes will live on as cultural shorthand long after the radio standard changes.

For officers in the field today, the practical answer is: learn both. Master your agency's current code list, but also practice transmitting in plain English. The next big incident — hurricane, mass shooting, civil unrest — may put you on the radio next to officers who do not share your code book. The ability to switch fluidly between code and plain language is now part of the job. Browse the rest of the law enforcement hub for guides on uniforms, discounts, academy training, degrees, and bilingual policing, or start the law enforcement practice test to gauge your overall readiness.