dBm to Watts Converter

dBm is power measured in decibels relative to 1 milliwatt (mW). It is a logarithmic scale, so every 10 dBm step multiplies power by 10 and every 3 dBm step roughly doubles it. By definition, 0 dBm equals 1 mW and 30 dBm equals 1 watt.

Use P(W) = 10^((dBm - 30) / 10). Subtract 30 from the dBm value, divide by 10, then raise 10 to that power. For example, 20 dBm gives 10^((20 - 30) / 10) = 10^-1 = 0.1 watt, which is 100 milliwatts.

Because dBm is referenced to 1 milliwatt, and 1 watt is 1,000 milliwatts. On the decibel scale that ratio is 10 x log10(1,000) = 30 dB, so 1 watt sits exactly 30 dBm above the 1 mW reference.

Yes. A negative dBm value means the power is below 1 milliwatt. For instance, -30 dBm is 1 microwatt, and received Wi-Fi or cellular signals are often between -50 dBm (strong) and -90 dBm (weak). This converter accepts negative dBm and shows the result in watts down to picowatts.

Use dBm = 10 x log10(P in watts) + 30, which is the same as 10 x log10(P in milliwatts). For example, 20 watts is 10 x log10(20) + 30, or about 43 dBm. Switch the direction in the converter to enter watts, milliwatts, or microwatts and read the dBm value.

Both are decibel power scales, but they use different references. dBm is relative to 1 milliwatt, while dBW is relative to 1 watt. Since 1 watt is 1,000 milliwatts, they differ by a fixed 30 dB: dBW = dBm - 30. So 30 dBm is the same power as 0 dBW.