Radiated Power Measurement

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Power Ratio dBm or dBmW

The power compared to a 1 milliwatt (1mW) source, expressed in decibels ( dB)

Formula:

<math> x = 10 \log_{10}(P/1 \ \mathrm{mW}) \, </math>

Where P is the power in watts (W)

This roughly equates to:

• Double the power = 3dB increase in dBm
• Halve the power = 3dB decrease in dBm

dBm level	Power
80 dBm	100 kW
60 dBm	1 kW = 1000 W
50 dBm	100 W
40 dBm	10 W
36 dBm	4 W
33 dBm	2 W
30 dBm	1 W = 1000 mW
27 dBm	500 mW
26 dBm	400 mW
25 dBm	316 mW
24 dBm	250 mW
23 dBm	200 mW
22 dBm	160 mW
21 dBm	125 mW
20 dBm	100 mW
15 dBm	32 mW
10 dBm	10 mW
6 dBm	4.0 mW
5 dBm	3.2 mW
4 dBm	2.5 mW
3 dBm	2.0 mW
2 dBm	1.6 mW
1 dBm	1.3 mW
0 dBm	1.0 mW = 1000 µW
−1 dBm	794 µW
−3 dBm	501 µW
−5 dBm	316 µW
−10 dBm	100 µW
−20 dBm	10 µW
−30 dBm	1.0 µW = 1000 nW
−40 dBm	100 nW
−50 dBm	10 nW
−60 dBm	1.0 nW = 1000 pW
−70 dBm	100 pW
−80 dBm	10 pW
−100 dBm	0.1 pW
−111 dBm	0.008 pW = 8 fW
−127.5 dBm	0.178 fW = 178 aW
−174 dBm	0.004 aW
−192.5 dBm	0.00004 aW
−∞ dBm	0 W

more information can be found here