dBm to Watts Converter
Convert signal power levels instantly.
What is dBm?
dBm (decibel-milliwatts) is the standard unit of power in radio frequency (RF), fiber optics, and audio engineering. It expresses power on a logarithmic scale relative to 1 milliwatt (1 mW).
Why do we use it? Because RF signals span a massive range. A WiFi signal (-70 dBm) is 10,000,000,000x weaker than a Microwave oven (+60 dBm). Logarithms let us work with these huge differences using simple 2-digit numbers.
Conversion Formulas
Converting between linear units (Watts) and logarithmic units (dBm) is essential for any RF engineer.
P(dBm) = 10 × log₁₀( P(mW) )
P(mW) = 10^( P(dBm) / 10 )
Common Benchmarks
- +30 dBm = 1 Watt (Typical Walkie Talkie)
- 0 dBm = 1 milliwatt (Bluetooth Earpiece)
- -100 dBm = 0.1 picowatts (GPS Signal)
- -174 dBm = Thermal Noise Floor (at room temp)
Practical Applications
- Signal Strength (RSSI): Your phone displays bars based on dBm. -60 dBm is full bars, -110 dBm is "No Service".
- Fiber Optics: Optical power is measured in dBm to calculate budget loss over long fiber runs.
- Audio Equipment: Professional audio gear uses dBu (referenced to 0.775V) and dBm (referenced to 1mW @ 600Ω).
FAQ
Is 0 dBm zero power?
No! 0 dBm is exactly 1 milliwatt. Zero power (0 Watts) is negative infinity dBm (-∞).
What does negative dBm mean?
It just means the power is less than 1 milliwatt. It does not mean negative energy! For example, -3 dBm is 0.5 mW. -10 dBm is 0.1 mW.
dBm vs dBi?
dBm is an absolute measure of power (Watts). dBi is a relative measure of antenna gain (Comparison). You add dBi to dBm to find the new output power (EIRP).