RF Utility

dBm to Watt Converter

Convert RF power between dBm, milliwatts and watts, and turn dB gain or loss into a linear ratio. Everything runs in your browser.

dBm to power

Watts (W)
Milliwatts (mW)
Microwatts (µW)

Power to dBm

Equivalent
dBm

dB gain / loss to ratio

Power ratio
Voltage ratio
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dBm, watts and the 10 dB rule

dBm is power referenced to 1 milliwatt on a logarithmic scale: 0 dBm = 1 mW, 30 dBm = 1 W. The formula is P(W) = 10^((dBm − 30) / 10). Because it is logarithmic, every 10 dB is a 10× change in power and every 3 dB is roughly double or half.

Power vs voltage ratio

A gain in dB maps to a power ratio of 10^(dB/10) and a voltage (amplitude) ratio of 10^(dB/20). Antenna gain, cable loss and receiver sensitivity in a link budget are all expressed in dB for exactly this reason: gains and losses simply add up.