Unit Converters · Browser · Free

dBm to Watts

Enter a power in dBm and this page shows the same power in watts. There is one number field.

What this tool does

It takes a power in dBm and gives the same power in watts. Type a dBm value into the number field and press Convert; nothing is worked out before you press it.

The result appears in a card below the button. Copy writes the result and its unit to the clipboard, and Clear resets the form.

How the numbers are shown

The conversion uses a power of ten, so many results run to a lot of decimal places. Every result is rounded to 15 significant digits and shown with ≈.

The rows of the table are the sort of values you get back: 0 dBm is ≈ 0.001 W, 20 dBm is ≈ 0.1 W and 30 dBm is ≈ 1 W.

The dBm to watts formula

P(W) = 10^(P(dBm) / 10) / 1000.

In words: take the dBm value, divide it by 10, use that as the exponent of 10, then divide by 1000. Following those steps on the 20 dBm row of the table gives 0.1 W.