MasterTool

dBm to Watts Converter

Convert RF power between dBm, watts, milliwatts and dBW in either direction.

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What this tool does

Convert RF power between dBm, watts, milliwatts and dBW in either direction. dBm is referenced to 1 mW and dBW to 1 W exactly; no impedance assumption is involved in power conversion.

How to use the dBm to Watts Converter

  1. Enter or select direction.
  2. Enter or select input value (dbm or watts, by direction).
  3. Read the calculated result; change any measurement to compare alternatives.

Formula

dBm → W: 10^((dBm − 30)/10); W → dBm: 10 × log10(W × 1000)
direction
Direction
value
Input value (dBm or watts, by direction)

dBm is referenced to 1 mW and dBW to 1 W exactly; no impedance assumption is involved in power conversion.

Worked example

For dbm to watts converter, the following measurements illustrate the exact method: Direction: dbm; Input value (dBm or watts, by direction): 30.

Inputs

  • DirectiondBm to watts
  • Input value (dBm or watts, by direction)30

Result

  • Power (W)1
  • Power (mW)1,000
  • Power (dBW)0

Results explained

Power (W)
Power (W) from the formula above. dBm is referenced to 1 mW and dBW to 1 W exactly; no impedance assumption is involved in power conversion.
Power (mW)
Power (mW) from the formula above. dBm is referenced to 1 mW and dBW to 1 W exactly; no impedance assumption is involved in power conversion.
Power (dBW)
Power (dBW) from the formula above. dBm is referenced to 1 mW and dBW to 1 W exactly; no impedance assumption is involved in power conversion.

Frequently asked questions

W = 10^((dBm − 30) ÷ 10). 30 dBm is exactly 1 W, 0 dBm is 1 mW, and every +10 dB multiplies power by ten.

Decibels relative to one milliwatt: dBm = 10 × log₁₀(power in mW). It is an absolute power level, unlike plain dB which is only a ratio.

10^((43 − 30)/10) = 10^1.3 ≈ 20 W — a typical mobile radio power level.

Decibels relative to one watt; dBW = dBm − 30. This tool shows it alongside watts and milliwatts.

Receiver signals are tiny: −90 dBm is 1 picowatt, far below 1 mW, so the logarithmic dBm scale keeps weak-signal numbers manageable.