Amateur Radio

dBm, or deci Bells milliwatt, what does it mean?

9 January 2022

Often when dealing with electronics you will see the measurement dBm, and if you know about how dB works in general you can easily get the gist of what it is saying. But, unlike most of our dB readings, dBm is actually anchored to the value of a milliwatt. Why does this matter? It makes it easier to compare disparate systems, or engineer connections between them. For instance, I used dBm to decide how many dB of attenuation I had to add to my HF radio to be able to pipe it output into my SDR so I could see what my signal looked like.

So without any further ado, let me show my annotated dBm to wattage chart that includes both useful info, and some useless trivia.

dBm to Wattage Chart
dBm	Watts	HF S Meter	VHF S Meter	Comments
-150 dBm	1.00 aW
-149 dBm	1.26 aW
-148 dBm	1.58 aW
-147 dBm	2.00 aW
-146 dBm	2.51 aW
-145 dBm	3.16 aW
-144 dBm	3.98 aW
-143 dBm	5.01 aW
-142 dBm	6.31 aW
-141 dBm	7.94 aW		S1
-140 dBm	10.00 aW
-139 dBm	12.59 aW
-138 dBm	15.85 aW
-137 dBm	19.95 aW
-136 dBm	25.12 aW
-135 dBm	31.62 aW		S2
-134 dBm	39.81 aW
-133 dBm	50.12 aW
-132 dBm	63.10 aW
-131 dBm	79.43 aW
-130 dBm	100.00 aW
-129 dBm	125.89 aW		S3
-128 dBm	158.49 aW
-127 dBm	199.53 aW
-126 dBm	251.19 aW
-125 dBm	316.23 aW
-124 dBm	398.11 aW
-123 dBm	501.19 aW		S4
-122 dBm	630.96 aW
-121 dBm	794.33 aW	S1
-120 dBm	1.00 fW
-119 dBm	1.26 fW
-118 dBm	1.58 fW
-117 dBm	2.00 fW		S5
-116 dBm	2.51 fW
-115 dBm	3.16 fW	S2
-114 dBm	3.98 fW
-113 dBm	5.01 fW
-112 dBm	6.31 fW
-111 dBm	7.94 fW		S6
-110 dBm	10.00 fW
-109 dBm	12.59 fW	S3
-108 dBm	15.85 fW
-107 dBm	19.95 fW
-106 dBm	25.12 fW
-105 dBm	31.62 fW		s7
-104 dBm	39.81 fW
-103 dBm	50.12 fW	S4
-102 dBm	63.10 fW
-101 dBm	79.43 fW
-100 dBm	100.00 fW
-99 dBm	125.89 fW		S8
-98 dBm	158.49 fW
-97 dBm	199.53 fW	S5
-96 dBm	251.19 fW
-95 dBm	316.23 fW
-94 dBm	398.11 fW
-93 dBm	501.19 fW		S9
-92 dBm	630.96 fW
-91 dBm	794.33 fW	S6
-90 dBm	1.00 pW
-89 dBm	1.26 pW
-88 dBm	1.58 pW
-87 dBm	2.00 pW
-86 dBm	2.51 pW
-85 dBm	3.16 pW	s7
-84 dBm	3.98 pW
-83 dBm	5.01 pW		S9 + 10 dB
-82 dBm	6.31 pW
-81 dBm	7.94 pW
-80 dBm	10.00 pW
-79 dBm	12.59 pW	S8
-78 dBm	15.85 pW
-77 dBm	19.95 pW
-76 dBm	25.12 pW
-75 dBm	31.62 pW
-74 dBm	39.81 pW
-73 dBm	50.12 pW	S9	S9 + 20 dB
-72 dBm	63.10 pW
-71 dBm	79.43 pW
-70 dBm	100.00 pW
-69 dBm	125.89 pW
-68 dBm	158.49 pW
-67 dBm	199.53 pW
-66 dBm	251.19 pW
-65 dBm	316.23 pW
-64 dBm	398.11 pW
-63 dBm	501.19 pW	S9 + 10 dB	S9 + 30 dB
-62 dBm	630.96 pW
-61 dBm	794.33 pW
-60 dBm	1.00 nW
-59 dBm	1.26 nW
-58 dBm	1.58 nW
-57 dBm	2.00 nW
-56 dBm	2.51 nW
-55 dBm	3.16 nW
-54 dBm	3.98 nW
-53 dBm	5.01 nW	S9 + 20 dB	S9 + 40 dB
-52 dBm	6.31 nW
-51 dBm	7.94 nW
-50 dBm	10.00 nW
-49 dBm	12.59 nW
-48 dBm	15.85 nW
-47 dBm	19.95 nW
-46 dBm	25.12 nW
-45 dBm	31.62 nW
-44 dBm	39.81 nW
-43 dBm	50.12 nW	S9 + 30 dB
-42 dBm	63.10 nW
-41 dBm	79.43 nW
-40 dBm	100.00 nW
-39 dBm	125.89 nW
-38 dBm	158.49 nW
-37 dBm	199.53 nW
-36 dBm	251.19 nW
-35 dBm	316.23 nW
-34 dBm	398.11 nW
-33 dBm	501.19 nW	S9 + 40 dB
-32 dBm	630.96 nW
-31 dBm	794.33 nW
-30 dBm	1.00 µW
-29 dBm	1.26 µW
-28 dBm	1.58 µW
-27 dBm	2.00 µW
-26 dBm	2.51 µW
-25 dBm	3.16 µW
-24 dBm	3.98 µW
-23 dBm	5.01 µW
-22 dBm	6.31 µW
-21 dBm	7.94 µW
-20 dBm	10.00 µW
-19 dBm	12.59 µW
-18 dBm	15.85 µW
-17 dBm	19.95 µW
-16 dBm	25.12 µW
-15 dBm	31.62 µW
-14 dBm	39.81 µW
-13 dBm	50.12 µW
-12 dBm	63.10 µW
-11 dBm	79.43 µW
-10 dBm	100.00 µW
-9 dBm	125.89 µW
-8 dBm	158.49 µW
-7 dBm	199.53 µW
-6 dBm	251.19 µW
-5 dBm	316.23 µW
-4 dBm	398.11 µW
-3 dBm	501.19 µW
-2 dBm	630.96 µW
-1 dBm	794.33 µW
0 dBm	1.00 mW			Max safe input power on most test equipment
1 dBm	1.26 mW
2 dBm	1.58 mW
3 dBm	2.00 mW
4 dBm	2.51 mW
5 dBm	3.16 mW
6 dBm	3.98 mW
7 dBm	5.01 mW
8 dBm	6.31 mW
9 dBm	7.94 mW
10 dBm	10.00 mW			Max peak input power SDR Play DX
11 dBm	12.59 mW
12 dBm	15.85 mW
13 dBm	19.95 mW
14 dBm	25.12 mW
15 dBm	31.62 mW
16 dBm	39.81 mW
17 dBm	50.12 mW
18 dBm	63.10 mW
19 dBm	79.43 mW
20 dBm	100.00 mW
21 dBm	125.89 mW
22 dBm	158.49 mW
23 dBm	199.53 mW
24 dBm	251.19 mW
25 dBm	316.23 mW
26 dBm	398.11 mW
27 dBm	501.19 mW			FRS max power channels 8-14
28 dBm	630.96 mW
29 dBm	794.33 mW
30 dBm	1.00 W
31 dBm	1.26 W
32 dBm	1.58 W
33 dBm	2.00 W			FRS max power channels 1-7,15-22
34 dBm	2.51 W
35 dBm	3.16 W
36 dBm	3.98 W
37 dBm	5.01 W			Max peak power most 2 meter and 70cm HT
38 dBm	6.31 W
39 dBm	7.94 W
40 dBm	10.00 W
41 dBm	12.59 W
42 dBm	15.85 W
43 dBm	19.95 W
44 dBm	25.12 W
45 dBm	31.62 W			Max power most 70 cm FM mobile radios
46 dBm	39.81 W
47 dBm	50.12 W			Max power most 2 meter FM mobile radios
48 dBm	63.10 W
49 dBm	79.43 W
50 dBm	100.00 W			Peak power on most ham radio HF base stations
51 dBm	125.89 W
52 dBm	158.49 W
53 dBm	199.53 W
54 dBm	251.19 W
55 dBm	316.23 W
56 dBm	398.11 W
57 dBm	501.19 W
58 dBm	630.96 W
59 dBm	794.33 W
60 dBm	1.00 kW
61 dBm	1.26 kW
62 dBm	1.58 kW			Amateur Radio Legal Limit
63 dBm	2.00 kW
64 dBm	2.51 kW
65 dBm	3.16 kW
66 dBm	3.98 kW
67 dBm	5.01 kW
68 dBm	6.31 kW
69 dBm	7.94 kW
70 dBm	10.00 kW
71 dBm	12.59 kW
72 dBm	15.85 kW
73 dBm	19.95 kW			Max power input of a 100 amp service US house
74 dBm	25.12 kW
75 dBm	31.62 kW
76 dBm	39.81 kW			Max power input of a 200 amp service US house
77 dBm	50.12 kW			Output power of KSL 1160 AM
78 dBm	63.10 kW
79 dBm	79.43 kW
80 dBm	100.00 kW			Max US Broadcast Radio Station Power
81 dBm	125.89 kW
82 dBm	158.49 kW
83 dBm	199.53 kW
84 dBm	251.19 kW
85 dBm	316.23 kW
86 dBm	398.11 kW
87 dBm	501.19 kW
88 dBm	630.96 kW
89 dBm	794.33 kW
90 dBm	1.00 MW
91 dBm	1.26 MW
92 dBm	1.58 MW
93 dBm	2.00 MW
94 dBm	2.51 MW
95 dBm	3.16 MW
96 dBm	3.98 MW
97 dBm	5.01 MW
98 dBm	6.31 MW
99 dBm	7.94 MW
100 dBm	10.00 MW
101 dBm	12.59 MW
102 dBm	15.85 MW
103 dBm	19.95 MW
104 dBm	25.12 MW
105 dBm	31.62 MW
106 dBm	39.81 MW
107 dBm	50.12 MW
108 dBm	63.10 MW
109 dBm	79.43 MW
110 dBm	100.00 MW
111 dBm	125.89 MW
112 dBm	158.49 MW
113 dBm	199.53 MW
114 dBm	251.19 MW
115 dBm	316.23 MW
116 dBm	398.11 MW
117 dBm	501.19 MW
118 dBm	630.96 MW
119 dBm	794.33 MW
120 dBm	1.00 GW
121 dBm	1.26 GW
122 dBm	1.58 GW
123 dBm	2.00 GW			Output from Hoover Dam

Resources

Bill & Megan Buhler Family Site