What is dBm?
A logarithmic ratio with a reference power of P0 = 1.000 milliwatt = 0 dBm.
dBm is defined as power ratio in decibel (dB) referenced to one milliwatt (mW) and the "m" in dBm stands for milliwatt.
With the known impedance value you can convert voltage V to level dBm (power) and vice versa.

Reference voltage at 600 ohms- 1 mW according to 0 dBm
600
Reference voltage at 50 Ohm - 1 mW according to 0 dBm
50



Enter two values, the third value will be calculated.
Voltage V, level L, and impedance
Z
Voltage V   V RMS
 Power level L   dBm re 1 mW 
Impedance Z   Ω
 


Table based on 50 Ohms

Vrms

dBm

Watts

 

Vrms

dBm

Watts

 

Vrms

dBm

Watts

μV

dBm

 

 

mV

dBm

 

 

V

dBm

W

0.7

-110

 10 fW

 

1.1

-46

 

 

1.1

+14

0.025

0.8

-109

S 3 

 

1.2

-45

 

 

1.2

+15

0.032

0.9

-108

 

 

1.4

-44

 

 

1.4

+16

0.04

1

-107

 

 

1.5

-43

 S 9 +30

 

1.5

+17

0.05

1.1

-106

 

 

1.7

-42

 

 

1.7

+18

0.063

1.2

-105

 

 

1.9

-41

 

 

1.9

+19

0.08

1.4

-104

 

 

2.2

-40

 100 nW

 

2.2

+20

0.1 W

1.5

-103

S 4 

 

2.5

-39

 

 

2.5

+21

0.13

1.7

-102

 

 

2.8

-38

 

 

2.8

+22

0.16

1.9

-101

 

 

3.1

-37

 

 

3.1

+23

0.2

2.2

-100

 100 fW

 

3.5

-36

 

 

3.5

+24

0.25

2.5

-99

 

 

3.9

-35

 

 

3.9

+25

0.3

2.8

-98

 

 

4.4

-34

 

 

4.4

+26

0.4

3.1

-97

S 5 

 

5

-33

S 9 +40 

 

5

+27

0.5

3.5

-96

 

 

5.6

-32

 

 

5.6

+28

0.63

3.9

-95

 

 

6.3

-31

 

 

6.3

+29

0.8

4.4

-94

 

 

7

-30

 1 W

 

7

+30

1 W

5

-93

S9 VHF/UHF

 

7.9

-29

 

 

7.9

+31

1.2

5.6

-92

 

 

8.9

-28

 

 

8.9

+32

1.5

6.3

-91

S 6 

 

9.9

-27

 

 

9.9

+33

2

7

-90

 1 pW

 

11

-26

 

 

11.2

+34

2.5

7.9

-89

 

 

13

-25

 

 

12.5

+35

3.1

8.9

-88

 

 

14

-24

 

 

14.1

+36

3.9

9.9

-87

 

 

15

-23

 

 

15.8

+37

5

11

-86

 

 

17

-22

 

 

17.7

+38

6.3

13

-85

S 7 

 

19

-21

 

 

19.9

+39

7.9

14

-84

 

 

22

-20

 10 W

 

22.3

+40

10 W

16

-83

 

 

25

-19

 

 

 

 

 

18

-82

 

 

28

-18

 

 

 

 

 

20

-81

 

 

32

-17

 

 

 

 

 

22

-80

 10 pW

 

35

-16

 

 

 

 

 

25

-79

S 8 

 

40

-15

 

 

 

 

 

28

-78

 

 

45

-14

 

 

 

 

 

32

-77

 

 

50

-13

 

 

 

 

 

35

-76

 

 

56

-12

 

 

 

 

 

40

-75

 

 

63

-11

 

 

 

 

 

45

-74

 

 

71

-10

 100 W

 

 

 

 

50

-73

S 9 

 

79

-9

 

 

 

 

 

56

-72

 

 

89

-8

 

 

 

 

 

63

-71

 

 

100

-7

 

 

 

 

 

71

-70

 100 pW

 

112

-6

 

 

 

 

 

79

-69

 

 

126

-5

 

 

 

 

 

89

-68

 

 

141

-4

 

 

 

 

 

100

-67

 

 

158

-3

 

 

 

 

 

112

-66

 

 

178

-2

 

 

 

 

 

126

-65

 

 

199

-1

 

 

 

 

 

141

-64

 

 

224

0

 1 mW

 

 

 

 

158

-63

 S 9 +10

 

251

+1

 

 

 

 

 

177

-62

 

 

282

+2

 

 

 

 

 

200

-61

 

 

316

+3

 

 

 

 

 

223

-60

 1 nW

 

354

+4

 

 

 

 

 

251

-59

 

 

398

+5

 

 

 

 

 

282

-58

 

 

446

+6

 

 

 

 

 

316

-57

 

 

501

+7

 

 

 

 

 

354

-56

 

 

562

+8

 

 

 

 

 

398

-55

 

 

630

+9

 

 

 

 

 

446

-54

 

 

707

+10

 10 mW

 

 

 

 

500

-53

S 9 +20 

 

793

+11

 

 

 

 

 

561

-52

 

 

890

+12

 

 

 

 

 

630

-51

 

 

1000

+13

 

 

 

 

 

707

-50

 10 nW

 

 

 

 

 

 

 

 

793

-49

 

 

 

 

 

 

 

 

 

890

-48

 

 

 

 

 

 

 

 

 

1000

-47

 

 

 

 

 

 

 

 

 

 



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