dBm / mW Converter
Convert power between dBm, mW, W and dBW by entering a single value, and compute the received power and the link margin by subtracting losses from the transmit power. Everything in your browser.
The power in all units
| Unit | Value | Definition |
|---|
Received power and link margin
Losses = cables + connectors + splices + FSPL or fiber attenuation
(all in dB). Prx = Tx + gains − losses;
Margin = Prx − Sensitivity.
How it is calculated · dBm, mW and margin
1. dBm is power on a logarithmic
scale referenced to 1 mW:
mW = 10^(dBm/10) and dBm = 10·log₁₀(mW).
2. Equivalences: W = mW / 1000,
µW = mW × 1000 and dBW = dBm − 30.
So 0 dBm = 1 mW and 30 dBm = 1 W.
3. Received power:
Prx (dBm) = Tx + gains − losses. In dB you add and
subtract directly (no multiplying), because the scale is already logarithmic.
4. Margin:
Margin = Prx − Sensitivity. If the margin is
positive the link works; if it is
negative the signal falls below the receiver threshold.
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How it works
The converter takes a single power value in dBm, mW or W and expresses it in every unit at once: dBm, mW, W, µW and dBW. It relies on the definition of dBm as power on a logarithmic scale referenced to 1 mW: mW = 10^(dBm/10) and dBm = 10·log₁₀(mW); from there come W = mW / 1000, µW = mW × 1000 and dBW = dBm − 30.
It also includes a received power and link margin section, useful for fiber optics and radio links: Prx (dBm) = Tx + gains − losses, where losses add up cables, connectors, splices and the attenuation of the medium (or FSPL in RF), all in dB. The margin is Prx − receiver sensitivity: if it is positive the link works; if negative the signal falls below the threshold and the verdict flags insufficient margin.
Example: a 10 dBm transmitter with 20 dB of losses
- Conversion:
10 dBm = 10^(10/10) = 10 mW(0.01 W, −20 dBW). - Received power:
Prx = 10 + 0 − 20 = −10 dBm, which equals 0.1 mW. - With a −30 dBm sensitivity, the margin is
−10 − (−30) = +20 dB: link OK with ample reserve.