RF calculator

dBm to milliwatts converter

Convert RF power between logarithmic dBm and linear milliwatts with the formula shown.

Need this in code or an AI agent? Call it as a free API.

Power in dBmdBmConverted power1.99526e-7 mW1.99526e-10 watts

Use these power levels on a real floor plan.

Start a project with this result

The inputs you see here come with you and prefill your first project.

Why dBm is logarithmic

dBm expresses power relative to one milliwatt. Zero dBm equals 1 mW, 10 dBm equals 10 mW, 20 dBm equals 100 mW, and 30 dBm equals 1 W. A 3 dB change is approximately a factor of two in power; a 10 dB change is exactly a factor of ten.

Negative dBm values are still positive powers below one milliwatt. For example, −30 dBm is 0.001 mW, or one microwatt.

To place the converted number in a propagation calculation, use the RF link-budget calculator.

What this doesn't model

Where a signal goes. Converting units says nothing about coverage.
Antenna gain, cable loss, and path loss, which the link budget calculator adds.

A SiteRF project takes transmit power and antenna settings per radio and calculates the resulting signal across the plan.

Related free tools

Free API

dBm and milliwatts conversion as an API

The same calculation over HTTP. Send the parameters in the query string or as JSON and get the result back with its formula and assumptions.

No API key. GET or POST. Every result carries its formula, assumptions, and source.

Try this endpoint in the docs OpenAPI spec

Request

curl -G "https://siterfapp.com/api/v1/tools/dbm-mw-conversion" \
  -d value=-67 \
  -d from=dbm

Response (abridged)

{
  "tool": "dbm-mw-conversion",
  "inputs": {
    "value": -67,
    "from": "dbm"
  },
  "result": {
    "dbm": -67,
    "milliwatts": 1.9952623149688787e-7,
    "watts": 1.9952623149688787e-10
  }
}