# dBu to dBm Calculator

This tool converts from dBu to dBm.

ðŸ”„ dBm to dBu

## Formula

dBm = dBu + 27.78 – 10*Log10(Z)

where Z is the impedance in ohm (Î©)

## Example Calculations

A value of 0 dBu is equivalent to 10.79 dBm or 0.012 Watt.

## Background

### What is dBu?

dBu is the RMS voltage relative to 0.7746 Volt.

1 VRMS is therefore equivalent to 20*Log10(1/0.7746) = 2.218 dBu.

The inverse relationship or conversion from dBu to VRMS is defined by the formula VRMS = 10(dBu / 20) x 0.7746.

Notes:

Where does 0.7746 come from?

It is the value of voltage that dissipates 1 milliwatt (mW) into a 600 ohm load. Reference: Wikipedia article on dB Voltage

V = âˆš(600Î© * 0.001W) Volt

dBu was originally dBv, however it was changed to what it is today to avoid confusion with dBV. Wikipedia Reference.

### What is dBm?

dBm stands for deciBel referenced to 1 milliwatt. It is an absolute unit of power and thereâ€™s an easyÂ conversion from Watt to dBm.

PdBm = 10*log10(1000*PW)

where

• PW is the power expressed in watt.
• PdBm is the power expressed in dBm