dBm ↔ Watt Converter

Convert RF/audio power levels between dBm and Watts instantly. Includes unit scaling and step-by-step Show Work.

How to Use

  1. Enter a value in dBm or Watts (only one is needed).
  2. Select the watt unit (µW/mW/W/kW) if using the Watt input.
  3. Results update instantly (the page URL will not change).
  4. Use Share Link to generate a restoreable URL on demand.
Inputs
Type in either field. The other updates automatically.
Examples: 0 dBm = 1 mW, 30 dBm = 1 W, 40 dBm = 10 W
Tip: dBm is referenced to 1 mW (0 dBm = 1 mW).
Quick Reference

Common points (exact, by definition)

dBm mW W
-300.001 mW0.000000001 W
-100.1 mW0.0001 W
01 mW0.001 W
1010 mW0.01 W
20100 mW0.1 W
301000 mW1 W
4010000 mW10 W
50100000 mW100 W

Definitions used: mW = 10^(dBm/10), W = 10^((dBm − 30)/10).

Show Work (step-by-step)
—
Work is shown using base definitions (dBm referenced to 1 mW).

Formulas

  • dBm → mW: mW = 10^(dBm/10)
  • dBm → W: W = 10^((dBm − 30)/10)
  • mW → dBm: dBm = 10 × log10(mW)
  • W → dBm: dBm = 10 × log10(W) + 30
Note: This converter is strictly power-based (dBm is referenced to 1 mW). No impedance is required.

FAQ

Is dBm dependent on impedance?

No. dBm is a power level referenced to 1 mW. Impedance matters when converting between voltage and dB units like dBV/dBu, not for dBm ↔ watts.

Why is 30 dBm equal to 1 watt?

Because 30 dB above 1 mW is a factor of 1000 in power: 1 mW × 1000 = 1000 mW = 1 W.

What about negative dBm values?

Negative dBm simply means less than 1 mW. Example: -10 dBm = 0.1 mW.

Tool Info

Last updated:

Updates may include additional formatting options, export helpers, and edge-case handling.