dB / dBm / watt / volt converter
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Value to convert
Conversions
dBm (ref 1 mW)
10·log10(P / 1 mW)
10 dBm
Watts
0.01 W
10 mW
Voltage (50 Ω)
V = √(P × 50)
0.7071 V RMS
dBV reading
relative to 1 V RMS (dBV)
-3.01 dBV
dB vs 0.775 V RMS (dBu)
0.775 V RMS (dBu)
-0.7963 dB
Linear power ratio
10^(dBm/10), relative to 1 mW
10×
About dB scales
A 3 dB change doubles or halves power; 10 dB is a factor of 10. dBm is always referenced to 1 mW, so 0 dBm = 1 mW, 10 dBm = 10 mW, 20 dBm = 100 mW, 30 dBm = 1 W. Voltage conversions assume a 50 Ω system (standard for RF) and an RMS measurement. Use the dBu reference when working against 600 Ω audio gear.
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