The U.S. 27 MHz FCC bandplan used in Citizens' band radio assigns 40 numbered radio frequency channels between 26.965MHz (channel 1) and 27.405MHz (channel 40), with channels generally spaced 10kHz apart.

There are odd 20kHz channel spacings between channels 3/4, 7/8, 11/12, 15/16 and 19/20. These 'unused' frequencies are used by remote controlled toys such as toy boats and toy cars. These frequencies cannot be used by remote controlled aircraft, due to interference by CB radio in close proximity, which could crash the plane or helicopter into the ground, an object, or even a person. For this reason model aircraft use only the 72.0~73.0MHz band instead, which contains 50 channels.

This assignment of channels to frequencies has been adopted by many countries worldwide, including the U.K, although some countries have only approved the use of the first 22 channels.

The channel/frequency allocation for the 40 channels are as follows:

Channel     Frequency
 
Channel 01   26.965 MHz
Channel 02   26.975 MHz
Channel 03   26.985 MHz
 
Channel 04   27.005 MHz
Channel 05   27.015 MHz
Channel 06   27.025 MHz
Channel 07   27.035 MHz
 
Channel 08   27.055 MHz
Channel 09   27.065 MHz  (emergency channel)
Channel 10   27.075 MHz
Channel 11   27.085 MHz
 
Channel 12   27.105 MHz
Channel 13   27.115 MHz
Channel 14   27.125 MHz
Channel 15   27.135 MHz
 
Channel 16   27.155 MHz
Channel 17   27.165 MHz
Channel 18   27.175 MHz
Channel 19   27.185 MHz
 
Channel 20   27.205 MHz
Channel 21   27.215 MHz
Channel 22   27.225 MHz
Channel 23   27.255 MHz
Channel 24   27.235 MHz
Channel 25   27.245 MHz
Channel 26   27.265 MHz
Channel 27   27.275 MHz
Channel 28   27.285 MHz
Channel 29   27.295 MHz
Channel 30   27.305 MHz
Channel 31   27.315 MHz
Channel 32   27.325 MHz
Channel 33   27.335 MHz
Channel 34   27.345 MHz
Channel 35   27.355 MHz
Channel 36   27.365 MHz
Channel 37   27.375 MHz
Channel 38   27.385 MHz
Channel 39   27.395 MHz
Channel 40   27.405 MHz

The frequency allocation list is supplied by the FCC (Federal Communications Commission) from Part 95 - Subpart D - Rules for CB Service Citizens Band (CB) Radio Service.

See also: GMRS, FRS, MURS