Volt to dBu Calculator

This tool converts RMS Voltage to dBu.

In what follows we also provide an overview of what dBu and RMS voltage mean.



???? dBu to Volt


dBu = 20*Log10(VRMS/0.7746)


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.


Where does the number 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

Image Credit: Omegatron

V = √(600Ω * 0.001W) Volt = 0.7746 V

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

What is RMS Voltage?

The Root mean square (RMS) voltage is the square root of the arithmetic mean of the squares of a set of voltage values.

RMS Value Formula

The formula for this is

VRMS = √(1/n)(V12 + V22 + … + Vn2)

where VRMS is the RMS value of the sequence of numbers V1, V2 … Vn.

Use the following calculators to find VRMS from

  1. A set of voltage values
  2. Peak or Average values of common waveforms

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