redzilla
Optical fiber

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.

Enter a value in dBm, mW or W and the other units are computed.

Examples
redzilla.cl — dbm
 
dBm
mW
W
dBW

The power in all units

UnitValueDefinition

Received power and link margin

Losses = cables + connectors + splices + FSPL or fiber attenuation (all in dB). Prx = Tx + gains − losses; Margin = Prx − Sensitivity.

Received power (Prx)
Link margin
Verdict
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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