Power Level (dBm, dBW) Converter
Convert signal and radio power between watts, milliwatts, microwatts and the decibel levels dBm and dBW.
Convert power level (dbm, dbw)
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Popular power level (dbm, dbw) conversions
Power Level (dBm, dBW) units
Every unit below converts to every other one in the calculator. Values are relative to the base unit, the watt (W).
| Unit | Symbol | System | Value |
|---|---|---|---|
| Milliwatt | mW | SI | = 0.001 W |
| Watt | W | SI | Base unit |
| Kilowatt | kW | SI | = 1000 W |
| Microwatt | µW | SI | = 0.000001 W |
| Decibel-watt | dBW | other | W = 10^(dBW ÷ 10) |
| Decibel-milliwatt | dBm | other | W = 0.001 × 10^(dBm ÷ 10) |
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About power level (dbm, dbw) units
A power level in dBm is 10 times the base-10 logarithm of the power in milliwatts, so 0 dBm is 1 mW and 30 dBm is 1 W. A level in dBW uses 1 watt as the reference, so 0 dBW is 1 W. The two differ by exactly 30: dBm = dBW + 30.
Decibels are used in radio, Wi-Fi, fiber optics and audio because signal powers span many orders of magnitude and because gains and losses add instead of multiply. A typical Wi-Fi transmitter sends about 20 dBm (100 mW) and a received signal of −60 dBm is only a nanowatt.
Frequently asked questions
- How do I convert dBm to watts?
- Divide the dBm value by 10, raise 10 to that power and multiply by 0.001. For example 30 dBm is 0.001 × 10³ = 1 W, and 0 dBm is 1 mW.
- What is the difference between dB, dBm and dBW?
- A plain dB is a ratio between two powers. dBm and dBW are levels: they compare a power with a fixed reference (1 mW or 1 W), so they describe an actual amount of power.
- Can I add two dBm values?
- Not directly. Adding gains in dB corresponds to multiplying powers, but two signals together add in watts. Two equal 0 dBm signals make 2 mW, which is about 3 dBm, not 0 dBm.
- Can zero watts be converted to dBm?
- No. The logarithm of zero is undefined, so zero power has no level in dBm. The calculator asks for a power greater than zero.