What Is the Wavelength of CB Radio?

CB radio is associated with the 11-meter band because its channels sit near 27 MHz. In the United States, CB uses 40 fixed channels from 26.965 MHz to 27.405 MHz, in the allocation identified by the FCC. That is why CB is commonly called the 11-meter band.

Use this table to translate the terms you will see on a CB radio, antenna, or product listing.

Term	CB Answer	What It Tells You
Wavelength	About 36 feet (11 meters)	CB antennas are designed around an 11-meter radio wave.
Frequency allocation	26.965 MHz to 27.405 MHz	This is the U.S. CB portion of the radio spectrum.
Channel plan	40 channels, each 10 kHz wide	A CB radio uses fixed numbered channels rather than an unrestricted tuning range.

What the CB Wavelength Means

A radio wave’s wavelength is the physical distance between matching points on successive waves. Frequency and wavelength move in opposite directions: lower-frequency signals have longer wavelengths, while higher-frequency signals have shorter ones.

Wavelength in meters = 300 ÷ frequency in MHz

At a nominal 27 MHz, the calculation is 300 ÷ 27, which equals about 11.1 meters. The exact wavelength changes slightly from one end of the CB allocation to the other, but “11 meters” is the useful name for the whole band.

This matters most when you choose an antenna. An antenna does not need to be a full wavelength long, but its design, length, loading coil, and tuning are all based on the frequency range it is meant to handle. A CB antenna is designed for the CB frequency range.

How to Choose Equipment for the CB Wavelength

Match the radio, antenna, and mounting setup to the same band. An antenna that physically connects to a CB radio is not automatically an antenna that will work well with it.

Your Situation	Look For	Avoid Assuming
Replacing a CB antenna	“CB,” “11 meter,” or “27 MHz” in the antenna description	That a 10-meter-only antenna is the same thing
Installing a mobile radio	A CB antenna, suitable vehicle mount, and compatible coaxial cable	That any metal mount makes a good antenna system
Listening only	An antenna that can receive around 27 MHz	That a receive-only antenna is suitable for transmitting
Buying a radio	A radio specifically intended for the CB service	That a radio covering nearby frequencies is a CB radio

Step 1: Identify the Band on the Radio and Antenna

Look at the radio’s label, channel display, or documentation for “CB,” “11 meter,” or “27 MHz.”
For a transmitting CB setup, confirm that the radio is intended for the U.S. CB allocation of 26.965 MHz to 27.405 MHz.
Read the antenna description before buying. The useful labels are “CB antenna,” “11-meter antenna,” or a stated frequency range that includes CB.

The band label matters more than an antenna’s appearance. A short whip may be a loaded CB antenna, while a longer-looking antenna may be intended for an entirely different band.

Step 2: Match the Antenna to the Installation

Choose a mobile antenna designed for vehicle use, or a base antenna designed for a fixed outdoor installation.
Use the proper mount and coaxial cable connection for that antenna type.
Keep the antenna clear of obstructions where practical, especially nearby metal that can affect its tuning and radiation pattern.

A full 11-meter antenna would be unwieldy for most vehicles, so mobile CB antennas commonly use loading coils to make a shorter physical antenna behave electrically like a longer one. That is why coil position, whip length, mount location, and vehicle grounding can all affect performance.

Step 3: Verify the System Before Normal Use

Connect the antenna securely before transmitting.
Check the antenna system with an appropriate SWR meter or antenna analyzer, using the procedure for that antenna and radio setup.
Start by listening on a channel to confirm that the radio receives local activity and background noise normally.
Make a brief test transmission.

A good antenna match helps the radio deliver its power to the antenna instead of reflecting energy back toward the transmitter.

How CB Channels Work

CB channels are numbered instead of freely selected across the whole 11-meter band. There are 40 numbered channels, and the channel plan uses 10 kHz-wide channels. Use the channel selector on the radio rather than trying to treat CB as an open tuning range.

The channel number is useful because other CB users can quickly agree where to listen. CB channels are shared; no channel belongs exclusively to one person or group. Listen first, then choose a clear channel when possible.

Channel 9 is reserved for emergency communications or traveler assistance. If you need that type of help, select Channel 9.

CB conversations should also leave room for other users. The FCC’s service guidance says you may not communicate with another station for more than 5 minutes continuously; after that, wait at least 1 minute before beginning another communication. The service rules are in 47 C.F.R. Part 95.

CB Radio and 10-Meter Radio Are Not the Same

CB and the neighboring amateur allocation are separate services, so their equipment labels should not be treated as interchangeable.

CB occupies the 11-meter band around 27 MHz. The nearby 10-meter amateur band begins at 28.000 MHz and runs to 29.700 MHz. The bands are close together on a frequency chart, but “close” is not the same as “compatible.”

This distinction can be confusing because some antennas, radios, and accessories are marketed with both CB and 10-meter terms. A dual-band or broadly adjustable product may be usable on more than one band when correctly configured.

When shopping, look for the band coverage in the specifications rather than relying on a product name.

How Wavelength Affects CB Range

The 11-meter wavelength helps explain antenna size. CB is intended for short-distance voice communication, and actual range depends heavily on the antenna system and the surrounding environment.

Important factors include:

Antenna quality, placement, height, and tuning
Nearby buildings, hills, trees, and vehicles
Electrical noise from power lines, electronics, and vehicle systems
The receiving station’s antenna and local noise level
Atmospheric conditions

At times, signals around 27 MHz can travel much farther than expected through ionospheric propagation. CB users often call this “skip.” It can make distant stations audible, but it can also make a normally quiet channel crowded and unreliable for local communication.

For dependable local use, focus on a properly installed CB antenna and a clear channel rather than trying to predict range from wavelength alone.

How to Confirm You Have a CB-Band Setup

Use this quick check before purchasing or installing equipment:

The radio is identified as a CB radio and has a numbered CB channel selector.
The antenna is identified for CB, 11 meters, or the 27 MHz region.
The coaxial cable and connectors fit both the radio and antenna mount correctly.
The antenna system has been checked for a proper match before regular transmitting.
You can receive signals or normal background noise when listening on a selected channel.
You understand which channel to use for emergency communications or traveler assistance.

Product descriptions may focus on 10 meters, amateur operation, VHF, UHF, GMRS, or marine radio rather than CB.

Frequently Asked Questions

Is CB Radio Shortwave?

CB uses high-frequency radio spectrum, but it is not usually what listeners mean by “shortwave radio.” In everyday use, shortwave usually refers to international broadcast listening across a broad range of frequencies, while CB is a two-way personal radio service with 40 fixed channels near 27 MHz.

How Far Does a CB Radio Transmit?

CB has no single guaranteed range. Antenna installation, terrain, local electrical noise, the other station’s antenna, and changing atmospheric conditions all affect how far a signal can be heard. Under favorable propagation conditions, 27 MHz signals can travel far beyond ordinary local coverage, but that should not be treated as dependable communication range.

What Meter Band Does CB Operate On?

CB operates on the 11-meter band. Its U.S. frequencies run from 26.965 MHz to 27.405 MHz, which corresponds to radio wavelengths around 36 feet. If you plan to transmit, check current requirements in the FCC’s Citizens Band Radio Service guidance before setting up or operating equipment.