dBm/Hz to dBm and Watt Calculator

dBm/Hz also called Power Spectral Density, is the amount of power in dBm per Hertz of bandwidth.

To convert dBm/Hz to dBm, enter the value and desired bandwidth in the calculator below.

The tool will calculate the power over this bandwidth and provide a value in both dBm and Watt.

Use this next calculator to convert from dBm to dBm/Hz. Enter the value and bandwidth

What is dBm/Hz used for?

The noise floor of a spectrum analyzer is specified in dBm/Hz. It’s the power of the signal measured in a 1 Hz resolution bandwidth. The measurement is normalized to 1 Hz.

The lower this value, the more sensitive the analyzer. The lowest noise floor that can be measured is -174 dBm/Hz.

Applications of this calculator

Compare Spectrum Analyzer Noise Floor

Many spectrum analyzer manufacturers use different bandwidth settings to specify their noise floor. For example TinySA‘s noise floor specifications are

Lowest discernible signal using a resolution bandwidth of 30 kHz of -102 dBm

The dBm to dBm/Hz calculator can be used to convert this to -147 dBm/Hz.

This can be compared with the noise floor of a Siglent Spectrum Analyzer which is more sensitive with a value of -161 dBm/Hz.

Convert between two different Resolution Bandwidths

Let’s say you want to convert a measurement that was made in a 30 kHz resolution bandwidth to 1 MHz resolution bandwidth.

  • Use the second calculator to normalize from dBm/ 30 kHz to dBm/Hz
  • Then enter this number in the first calculator along with the desired bandwidth of 1 MHz. This will convert from dBm/Hz to dBm/ 1 MHz