RF & Telecommunications Tool Decibel Power Scale
dBm to Watts Calculator — RF & Audio Decibel-Milliwatts
Convert logarithmic signal levels (dBm and dBW) to electrical power in Watts and milliwatts, with RMS voltage across 50Ω and 600Ω loads.
RF & Audio Telecommunications
dBm to Watts & Volts Calculator
Convert decibel-milliwatts (dBm) into linear electrical watts, milliwatts, and RMS voltage.
P(mW) = 10^(dBm / 10) • P(W) = 10^((dBm - 30) / 10)
+30.0 dBm
Impedance determines the resulting AC RMS voltage generated across the termination load.
Calculated Linear Electrical Power
1.000 W
Power in Milliwatts (mW): 1,000.0 mW
Power in Microwatts (μW): 1,000,000 μW
RMS Voltage Across Load: 7.071 V RMS
Decibels relative to 1 Watt (dBW): 0.00 dBW
Mathematical Substitution:
P = 10^((30 - 30) / 10) = 10^0 = 1.000 Watts
*0 dBm is defined as exactly 1.0 milliwatt dissipated into a termination load. True RMS AC voltage calculated via V = √(P · Z).
Logarithmic Power Conversion Formulas (dBm & dBW)
The decibel-milliwatt (dBm) is a logarithmic unit of power ratio referenced to 1.0 milliwatt (1 mW = 0.001 W):
The dBm Conversion Equations
Power (Watts) = 10^((dBm - 30) / 10) = 0.001 · 10^(dBm / 10)
Signal Level (dBm) = 10 · log₁₀(Power_Watts / 0.001) = 10 · log₁₀(Power_mW)
Voltage @ 50 Ω (V_RMS) = √(Power_Watts · 50 Ω)
dBm to Watts & Voltage Reference Matrix
| Signal Level (dBm) | Power in dBW | Power in Watts | RMS Voltage @ 50 Ω | Typical Real-World Application |
|---|---|---|---|---|
| -30 dBm | -60 dBW | 1.0 μW (0.000001 W) | 0.0071 V RMS | Receiver Sensitivity Threshold |
| -10 dBm | -40 dBW | 0.1 mW (0.0001 W) | 0.0707 V RMS | Consumer Line-Level Audio (-10 dBV) |
| 0 dBm | -30 dBW | 1.0 mW (0.001 W) | 0.2236 V RMS | Standard Telecommunications Reference |
| +10 dBm | -20 dBW | 10.0 mW (0.010 W) | 0.7071 V RMS | Bluetooth Class 2 Transmitter |
| +20 dBm | -10 dBW | 100.0 mW (0.100 W) | 2.236 V RMS | Wi-Fi Router Max Transmit Power |
| +30 dBm | 0 dBW | 1.000 Watt | 7.071 V RMS | Handheld UHF Walkie-Talkie |
| +40 dBm | +10 dBW | 10.00 Watts | 22.36 V RMS | Cellular Base Station Sector |
| +50 dBm | +20 dBW | 100.0 Watts | 70.71 V RMS | FM Broadcast Exciter |
| +60 dBm | +30 dBW | 1,000 Watts (1 kW) | 223.6 V RMS | High-Power Television Transmitter |
Frequently Asked Questions
0 dBm is defined as exactly 1.0 milliwatt (0.001 Watt) of power dissipated into a load. Across a standard 50-Ohm RF load, 0 dBm produces 0.2236 Volts RMS.
dBm is referenced to 1 milliwatt (1 mW), whereas dBW is referenced to 1 Watt (1,000 mW). Therefore: dBW = dBm - 30 dB. For example, +30 dBm = 0 dBW = 1.0 Watt.
Doubling power in Watts increases the signal level by approximately +3.01 dBm (10 × log10(2)). For example, 1 Watt (+30 dBm) doubled to 2 Watts equals +33.01 dBm.
50 Ohms represents the optimal compromise between maximum power handling capability (which occurs near 30 Ohms in coaxial cables) and minimum signal attenuation loss (which occurs near 77 Ohms).
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