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dBm to Watts Converter

P(W) = 10^((dBm − 30)/10). 0 dBm is 1 mW.

By Jasper · Updated

Calculator

PASS0 dBm = 1 mW-30.00 dBW

P(W) = 10^((dBm − 30)/10). Fill dBm or watts, not both. 0 dBm = 1 mW; dBW = dBm − 30.

dBm
0 dBm
W
1 mW
dBW
-30.00 dBW
  • Pass dBm ↔ W: 0.00000 dBm = 0.00100000 W = -30.0000 dBW

Formula

dBm to watts

P=10(dBm-30)/10 P(W) = 10^((dBm − 30)/10)

dBW

dBW=dBm-30 dBW = dBm − 30

Variables

Symbol Meaning Unit Typical range Precision Default
dBm Power dBm — 4 sig 0 dBm
P Power (optional, instead of dBm) W — 4 sig
dBW Power dBW — 4 sig —

Worked example

0 dBm = 1 mW

Input Value
dBm · Power 0 dBm
Output Value
P · Power (optional, instead of dBm) 1 mW
dBW · Power -30 dBW

30 dBm = 1 W

Input Value
dBm · Power 30 dBm
Output Value
P · Power (optional, instead of dBm) 1 W
dBW · Power 0 dBW

5 W

Input Value
P · Power (optional, instead of dBm) 5 W
Output Value
dBm · Power 36.99 dBm
dBW · Power 6.99 dBW

How it works

RF power is usually written in dBm so you can add gains and losses. Converting back to watts is a one-line exponent; this page also reports dBW.

Enter dBm or watts. The other representations follow. This is a unit conversion, not a link budget.

Pitfalls

  • Filling both dBm and watts. Leave one field empty.
  • Taking the log of a non-positive wattage — watts must be > 0.
  • Mixing dBm (1 mW reference) with dBW (1 W reference) without the 30 dB shift.

FAQ

How many watts is 0 dBm?

1 mW.

How many watts is 30 dBm?

1 W. That is also 0 dBW.

What is dBW?

dBW = dBm − 30. It is the same power referred to 1 W instead of 1 mW.

Can I convert milliwatts?

Yes. Pick mW in the watts unit selector, or enter 0.001 W.

Related

Sources