The dbm Calculator & Reference table for 50 Ohms
Logo

Index
 Aerial Calculations 
 Balun Theory 
 Beacon Listings Vhf Uhf 
 Calculating Freq 
 Coax Cable Spec 
 Ic821h Mods 
 Kenwood Ts2000 
 Kenwood Ts870 
 Kenwood Ts890 
 M0ebj S Match 
 Prefix List 
 Q Codes 
 Radio Mods 
 Uk Repeater 
 Watt Converter 
 
Go to the Home Page : Amateur Radio
-   Callsign lookup
Help

The dbm Calculator & Reference table for 50 Ohms


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