Measured sensitivity of a UV-5R is made as follows: an LF signal of frequency 1 kHz is FM modulated over a width of 10 kHz and sent to the input of UV-5R. The FM signal level is increased until the 1 kHz signal becomes perceptible to the ear.
In the 145 MHz band, this level corresponds to -30 dBuV or 0.03 uV
In the 435 MHz band, this level corresponds to -16.5 dBuV or 0.15 uV
In the VHF band the squelch level and the corresponding voltage (10 kHz FM channel) are shown in the figure below.