dBm calculator - conversion voltage V to dB dBu dBV dBm mW Checker
 
Deutsche Version UK-flag s/w - sengpielaudio D-flag - sengpielaudio
 
• Conversion: Voltage V to Level  dB, dBu, dBV, and dBm •

Usually we measure AC voltage V as voltsRMS.

Voltage V:  volts (Root Mean Square RMS)
     
         ↓         
     
Voltage level L:  
L =  dBu reference: 0.775 V
L =  dBV reference: 1 V
Power level L: Not used for audio
L =  dBm > > >   ref. 1 mW at ohms
The index u at decibel (dB) means unloaded source, V (volt). Some say: The "u" in dBu
implies also that the load impedance is unspecified, or unterminated and is likely to be high.
The index m at dB (decibel) means 1 milliwatt (power) as reference value for 0 dB.

If the reverse conversion dBu, or dBV to volts is needed, go to the converter at the bottom.

What is dBu? A logarithmic voltage ratio with a reference voltage of V0= 0.7746 volt ≡ 0 dBu
What is dBV? A logarithmic voltage ratio with a reference voltage of V0 = 1.0000 volt ≡ 0 dBV
The max. home recording level of −10 dBV means 0.3162 volts, that is −7.78 dBu

Level   Formula volt to level        Voltage   Formula level to volt

Rainbow line

• What is dBm? A logarithmic ratio with a reference power of P0 = 1.000 milliwatt ≡ 0 dBm
The dBm is not used in audio engineering. With the known impedance value you can convert
voltage V to level dBm (power) and vice versa.

For radio frequency systems (RF), power matching or impedance matching is
absolutely essential.

• The dBm calculator for power matching or impedance matching •

Enter two values, the third value will be calculated.
Voltage V, level L, and impedance Z

Voltage V   V RMS
 Power level L   dBm re 1 mW 
Impedance Z   Ω
 

dBm indicates that the reference power is P0 = 1 milliwatt = 0.001 watt ≡ 0 dB

Electric power (telephone) P:
watts		  ↔  Electric Power level LP
dBm
Start   Start
Reference power P0 = 1 milliwatt (mW) = 0.001 W ≡ 0 dBm
Reference voltage at 600 ohms - 1 mW according to 0 dBm
weiter
Reference voltage at 50 Ohm - 1 mW according to 0 dBm
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• Definition of dBm

dBm is defined as power ratio in decibel (dB) referenced to one milliwatt (mW). It is an
abbreviation for dB with respect to 1 mW and the "m" in dBm stands for milliwatt.

dBm is different from dB. dBm represents absolute power, whereas in audio engineering the
decibel is usually a voltage ratio of two values and is used then to represent gain or attenuation
of an audio amplifier, or an audio damping pad.

If you use modern audio equipment in sound engineering, above calculators for usually
600 ohms impedance for telephone lines or antennas are of no value. Matching impedance for
power is not used anymore. You will only use voltage bridging or impedance bridging.

Here you find your adequate calculator for voltage and voltage level:

Converter: Decibel to Voltage and vice versa

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