dB / dBm / Watts Converter
Instant power and ratio conversions for RF work. Edit any field — the others follow, and the URL stays shareable as-is.
0 dBm = 1 mW
30 dBm = 1 W
Edit any field — the others follow
2× ≈ 3.01 dB
Negative dB = a loss (ratio below 1)
What this checks & why
dBm is absolute power on a logarithmic scale referenced to 1 milliwatt: 0 dBm = 1 mW, 30 dBm = 1 W, and every +10 dB is a ×10 in power. RF work lives on this scale because gains and losses then add instead of multiply — a 20 W repeater is just 43 dBm.
Plain dB (the second pair) is a ratio, not a power: +3 dB is double, −3 dB is half. Zero or negative watts have no dB representation, which is why those inputs show a note instead of a number.