Convert dBm to watts, milliwatts, microwatts, and dBW. Bidirectional converter with Vrms for 50Ω systems and a practical reference table.
The dBm to watts converter translates between decibel-milliwatts (dBm) and linear power units — watts, milliwatts, and microwatts. dBm is the standard logarithmic power unit in RF engineering, telecommunications, fiber optics, and wireless networking.
The converter works bidirectionally: enter dBm to get watts, or enter watts to get dBm. It also calculates dBW (decibels relative to 1 watt) and the RMS voltage across a standard 50Ω impedance — essential for RF circuit design.
A reference table spanning −90 to +90 dBm covers the full range from barely detectable signals to high-power transmitters, and a practical applications table maps dBm values to real-world wireless scenarios. This helps users move between spectrum analyzer readings, transmitter specs, and power budgets without manual logarithm errors. It is especially useful during link budget reviews, antenna testing, and troubleshooting when teams must align readings from different instruments and reporting formats in production networks and training materials.
RF engineers, network technicians, and wireless enthusiasts need to convert between logarithmic (dBm) and linear (watts) power constantly. This tool handles the math and provides real-world context for the values when planning links, tuning devices, documenting measurements, and explaining signal levels to non-specialists in project reviews and handoffs. It also speeds up troubleshooting under time pressure.
Watts = 10^(dBm / 10) / 1000. dBm = 10 × log₁₀(Watts × 1000). dBW = dBm − 30. Vrms = √(Watts × 50) for 50Ω.
Result: 20 dBm = 0.1 W = 100 mW = −10 dBW = 2.236 Vrms (50 Ω)
10^(20/10) / 1000 = 100/1000 = 0.1 watts = 100 mW. dBW = 20 − 30 = −10 dBW. Vrms = √(0.1 × 50) = 2.236 V.
dBm uses a logarithmic scale with 1 milliwatt as the reference. Every +10 dBm multiplies power by 10, every −10 dBm divides by 10. This makes it easy to handle the enormous range of power levels in RF systems — from femtowatt-level satellite signals to kilowatt transmitters.
RF systems standardize on 50Ω impedance (75Ω for cable TV). The voltage across a 50Ω load at a given power level is: V = √(P × 50). This voltage is important for amplifier design, antenna matching, and signal integrity analysis.
Your phone displays Wi-Fi signal strength in dBm (usually in settings > Wi-Fi > signal details). A reading of −45 dBm means you're close to the router. At −80 dBm, you're at the fringe of usable range. Understanding dBm helps diagnose connectivity issues.
dBm stands for "decibels relative to one milliwatt." It is a logarithmic power unit where 0 dBm = 1 mW.
Watts = 10^(dBm / 10) / 1000. Example: 20 dBm → 10^(20/10) / 1000 = 0.1 W.
dBm references 1 milliwatt; dBW references 1 watt. dBW = dBm − 30.
−30 to −50 dBm is excellent. −50 to −60 dBm is good. −60 to −70 dBm is usable. Below −80 dBm is poor.
Logarithmic scales compress huge ranges into manageable numbers. RF power spans from picowatts to kilowatts — that is 15 orders of magnitude, but only −90 to +90 dBm.
10^(3/10) = 1.995 ≈ 2. So adding 3 dB to any power level approximately doubles the linear power.