dB Calculator

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)

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