Noise Floor Calculator

The tool calculates the thermal noise floor of a radio receiver.

Enter the:

  • Temperature in either Kelvin or Celsius
  • Bandwidth
  • Noise Figure in dB

Noise Floor of a Radio Receiver

In a radio receiver, the noise floor is the level below which a signal will not be detected. In practice, a signal has to be at least a few dB higher before it can be detected.

Spectrum analyzers have a specification called the Displayed Average Noise Level (DANL) which is the same as the Noise Floor. It depends on frequency and is normalized to 1 Hz bandwidth (dBm/Hz).

Example Noise Floor Calculation

For a temperature of 27oC, 100 MHz Bandwidth and a noise figure of 3 dB, the noise floor is -90.83 dBm.