Police Scanner Codes Explained: The Complete 10-Code List

Where Scanner Codes Came From

Ten-codes were invented for a technical reason that no longer exists. In 1937, Illinois State Police communications director Charles Hopper was dealing with early radios built around vacuum tubes and dynamotors, which needed a moment to spin up to full power. The first syllable of any transmission got clipped. Prefixing everything with "ten" gave the transmitter time to reach full power before the meaningful part of the message arrived.

The Association of Public-Safety Communications Officials, APCO, developed those signals into a published list, expanded it through the 1960s, and issued the version most people mean when they say "the ten-codes" in APCO Project 14 in 1974.

The clipping problem was solved decades ago. The codes stuck around anyway, because by then they were faster to say than the phrases they replaced and everyone on the channel already knew them.

The One Thing to Know Before You Read Any Code List

APCO's list was a recommendation, not a mandate. Agencies were free to adopt it, modify it, or ignore it, and over eighty years plenty did all three. It is genuinely rare to find two agencies whose code sets match exactly.

So treat the list below as the baseline, not the law. It will get you most of the way on most feeds, and where your local agency does something different, you will usually be able to tell from context within a few minutes of listening.

You don't need to buy a physical radio to hear any of this. The easiest way to start is to download Scanner Radio on your phone. It's free.

The Complete APCO 10-Code List

This is the full APCO list, 10-0 through 10-99. Most agencies use only a fraction of it day to day, and the ones you will hear over and over on a typical feed are 10-4, 10-7, 10-8, 10-9 and 10-20. The rest are worth having when something unusual comes across the channel.

Response Codes: Code 1 Through Code 7

Response codes are separate from ten-codes and answer a different question. A ten-code says what is happening. A response code says how fast to get there.

California Codes You Will Hear Far Outside California

California never fully adopted the APCO list. It built its own, and because so much film and television is made in Los Angeles, its numbers leaked into the national vocabulary. Plenty of people know what a 187 is without ever having heard one on an actual radio.

Two things worth knowing: the 11-series covers traffic, and the bare three and four digit numbers are statute sections, not radio codes. They only mean anything in a state whose code book uses those numbers.

Fire and EMS Radio Terms

Fire and EMS traffic sounds different from police traffic, and the difference trips up a lot of new listeners. Fire ground communication leans on plain-language terminology rather than numeric codes, partly because it has to work when three departments from three counties show up at the same building.

These are the terms that carry the most information on a fire feed.

The Police Phonetic Alphabet

When an officer spells a plate or a name, they are usually not using the military alphabet. APCO formally switched to the international NATO alphabet in 1974, and most American police departments simply never went along with it. The 1940 Adam-Boy-Charles set is still what you will hear on the majority of US police feeds.

How to Find the Codes for Your Area

This is the question that brings most people to a page like this, and it deserves an honest answer: no list on the internet can tell you your local codes with certainty, because your local agency decided them and may not have written them down publicly.

What does work, in rough order of effort:

• Start from the APCO list above and listen for mismatches. Most agencies are closer to it than not. You will spot the departures fast, because they will be the codes that keep appearing in situations the APCO meaning does not fit.
• Check whether your agency publishes its radio procedures. Many departments post general orders or standard operating procedures as public PDFs, and codes are often in an appendix.
• Look at your county 911 or emergency communications center. Dispatch centers serve multiple agencies and frequently publish a shared code list, which is usually the authoritative one for the whole county.
• Listen to dispatch rather than the units. Dispatchers repeat and confirm things for the record, so they give away meanings that officers assume everyone knows.
• Note the context, not the number. A code you hear only at 7am and 7pm is a shift change. One that always precedes a tow truck is a collision. You can decode most of a local set this way in a week.

Opening a feed for your own city and following along for twenty minutes teaches you more than any list will. Pick the busiest feed your area has rather than the quietest, since a channel with steady traffic gives you far more repetitions to learn from.

One more thing that helps while you are still learning a local set: on Scanner Radio, listeners tag the type of incident happening on a feed as it unfolds, and those tags surface as headlines alongside the audio. You can see at a glance what kind of event is in progress, which is useful context when a quiet channel suddenly gets busy.

Why Departments Are Moving to Plain Language

The 10-13 problem stopped being theoretical in 2005. During the response to Hurricane Katrina, responders from different jurisdictions found they could not reliably understand each other's radio codes, and after-action reviews of the September 11 response had already flagged the same failure.

FEMA subsequently discouraged ten-codes precisely because their meanings varied so widely. The Department of Homeland Security's SAFECOM program has published guidance on moving to plain language, and ten-codes are not permitted at all in the national Incident Command System, the framework agencies use when multiple organizations work one incident. Nineteen states had switched to plain English by the end of 2009.

Most departments landed on a hybrid. Plain language for anything urgent or shared across agencies, and a handful of retained ten-codes for routine status, which is why 10-8 and 10-7 have outlived almost everything else on the list. If you want a sense of how the whole chain fits together, our piece on how emergency dispatch works covers what happens between the call and the radio traffic.

For listeners this is straightforwardly good news. A feed that says "structure fire, heavy smoke showing, second alarm" is far easier to follow than one that says 10-70 and expects you to know whose 10-70 it is.

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