dB Calculator

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dB Calculator

Input Voltage (V) Input Power (W) Reference Voltage (V) Reference Power (W) Gain (dB) Gain (dB) <input type="button" value="Voltage  Power"> Vpp mVpp Vrms mVrms dBV dBmV Impedance (Ohms) dBm dBW Wrms mWrms

dB Definitions

Unit	Usage	Definition
Bel	power	logarithm (10) of the ratio of two powers
dB		decibel = 1/10 Bel
dBA		The dB SPL figure with a weighting curve applied to it
dBc		dB referenced to a carrier (voltage or power)
dBf	power	dB referenced to a femtowatt
dBi	power	dB change of an antenna system relative to an isotropic radiator
dBK	power	dB referenced to a kilowatt
dBm	power	dB referenced to a milliwatt
dBmV	voltage	dB referenced to 1 mVrms across 75 ohms
(dBS)		(direct broadcast satellite)
dB SPL	power	dB referenced to 20 uPascals
dBu	voltage	dB referenced to 0.775 Vrms across 600 ohms Sometimes dB referenced to 1 uVrms, hence the alternate terminology below to avoid confusion
dBv	voltage	Alternate for terminology for dBu (referenced to 0.775 Vrms)
dBV	voltage	dB referenced to 1 Vrms
dBW	power	dB referenced to 1 Watt
dBx		dB above reference coupling (crosstalk)

Important Relationships

Voltage Vpp Vpeak Vrms dBV 10000 5000 3535.5339 80 1000 500 353.55339 60 100 50 35.355339 40 10 5 3.5355339 20 3.16227766 1.5811388 1.118034 10 2 1 0.7071068 6.0205999 1.99526231 0.9976312 0.7054318 6 1.41253754 0.7062688 0.4994074 3 1 0.5 0.3535534 0 0.70794578 0.3539729 0.2502966 -3 0.50118723 0.2505936 0.1771964 -6 0.5 0.25 0.1767767 -6.0205999 0.31622777 0.1581139 0.1118034 -10 0.1 0.05 0.0353553 -20 0.01 0.005 0.0035355 -40 0.001 0.0005 0.0003536 -60 0.0001 0.00005 3.536E-05 -80				Power Wrms dBK dBW dBm 141421.36 20 50 80 14142.136 10 40 70 1414.2136 0 30 60 141.42136 -10 20 50 14.142136 -20 10 40 2.8284271 -26.9897 3.0103 33.0103 1.4142136 -30 0 30 0.7071068 -33.0103 -3.0103 26.9897 0.1414214 -40 -10 20 0.0141421 -50 -20 10 0.0014142 -60 -30 0 0.0001414 -70 -40 -10 1.414E-05 -80 -50 -20