The dBm to Watt Converter
Convert dBm to watts and milliwatts, and back again, for transmit power, link budgets, and receiver sensitivity figures.
What is dBm to Watts Converter and how to use it?
This free dBm converter handles RF power conversion in both directions: dBm to watts, dBm to mW, watts to dBm, and kW to dBm. It is built for RF engineers, fiber techs, wireless planners, and audio engineers who need a fast dBm calculator on-site, on a bench, or up a tower with a phone in one hand.
To use it, pick the unit you are converting from in the dropdown next to Power and type your value. Pick the unit you want to see in the dropdown next to Result, and the converted value appears instantly as you type. Tap the swap button between the two fields to reverse the conversion in one move, or use Copy result to copy the converted value with its unit straight to your clipboard.
RF Power Converter
Choose an input unit and an output unit, then type. Use the swap button to reverse the conversion in one tap.
Please enter a valid number. Power in mW, W, or kW must be greater than zero.
Common dBm to watts reference values
| dBm | mW | W | Typical use |
|---|---|---|---|
| -30 | 0.001 | 0.000001 | Receiver noise floor, weak off-air signal |
| -10 | 0.1 | 0.0001 | Typical received Wi-Fi signal at distance |
| 0 | 1 | 0.001 | Bluetooth Class 2, reference level |
| 10 | 10 | 0.01 | Wi-Fi client device, low-power sensor radio |
| 20 | 100 | 0.1 | Standard Wi-Fi access point output |
| 23 | 200 | 0.2 | High-power AP or small cell output |
| 27 | 500 | 0.5 | 5 GHz point-to-point client radio |
| 30 | 1000 | 1 | Licensed band microwave link radio |
| 36 | 4000 | 4 | Maximum EIRP, 2.4 GHz ISM band (FCC) |
| 43 | 20000 | 20 | Cellular base station sector output |
| 50 | 100000 | 100 | High-power telemetry or paging transmitter |
| 60 | 1000000 | 1000 | FM broadcast transmitter (1 kW) |
What is dBm and why does RF work use it?
dBm is an absolute power level referenced to 1 milliwatt. Zero dBm equals 1 mW, and every 10 dB step is a tenfold change in power, so this dBm calculator is really a logarithmic power conversion tool. When you convert watts to dBm, you are taking the base-10 logarithm of the power ratio and scaling it by ten. The math is simple: dBm equals 10 times log10 of the power in mW.
RF engineers use logarithmic units because radio systems span an enormous dynamic range. A cellular base station transmitting at 43 dBm and a receiver picking up a signal at minus 100 dBm sit more than 140 dB apart, which is a power ratio in the trillions. Log units turn that range into manageable addition and subtraction. Link budgets, antenna gains, cable losses, and filter insertion losses all combine by simple arithmetic once everything is in dB or dBm, which is why a reliable dBm to watts converter lives in every RF engineer's bookmarks.
One practical habit: when you use a tool like this for dBm to mW conversion, remember that 3 dB is a doubling of power and 10 dB is ten times the power. That mental shortcut lets you sanity-check any RF power conversion before you trust the numbers on a datasheet.
This converter is also useful when comparing spec sheets across vendors, since some manufacturers list transmit power in dBm while others use watts or milliwatts. Converting both figures to the same unit before comparing radios, antennas, or amplifiers avoids the kind of mismatch that leads to an inaccurate link budget.
Tip: bookmark this dBm to watts converter for your next site survey. All calculations run locally in your browser, so it works offline once the page has loaded.