DBm

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DBm

For other uses, see DBM (disambiguation)
DBm

For other uses, see DBMdBm is an abbreviation for the power ratio in decibels of the measured power referenced to one milliwatt . It is used in radio, microwave and fiber optic networks as a convenient measure of absolute power because of its capability to express both very large and very small values in a short form....

dBm (sometimes dBmW) is an abbreviation for the power ratio in decibels (dB) of the measured power referenced to one milliwatt (mW). It is used in radio, microwave and fiber optic networks as a convenient measure of absolute power

Power (physics)

In physics, power is the rate at which mechanical work is performed or energy is transmitted, or the amount of energy required or expended for a given unit of time....
because of its capability to express both very large and very small values in a short form. Compare dBW, which is referenced to one watt (1000 mW).

Since it is referenced to the watt

WATT

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Power (physics)

WATT

WATT is a radio station broadcasting a News radio-Talk radio-Sports radio format. Licensed to Cadillac, Michigan, it first began broadcasting in 1945....
, it is an absolute unit, used when measuring absolute power. By comparison, the decibel (dB) is a dimensionless unit, used for quantifying the ratio between two values, such as signal-to-noise ratio

Signal-to-noise ratio

Signal-to-noise ratio is an electrical engineering measurement, also used in other fields , defined as the ratio of a signal power to the noise power corrupting the signal....
.

Unit conversions

Zero dBm equals one milliwatt. A 3 dB increase represents roughly doubling the power, which means that 3 dBm equals roughly 2 mW. For a 3 dB decrease, the power is reduced by about one half, making -3 dBm equal to about 0.5 milliwatt. To express an arbitrary power P as x dBm, or go in the other direction, the following equations may be used:

or

and

where P is the power in W and x is the power ratio in dBm. Below is a table summarizing useful cases:

dBm level	Power	Notes
80 dBm	100 kW	Typical transmission power Effective radiated power In radio telecommunications, effective radiated power or equivalent radiated power is a standardized theoretical measurement of Radio frequency energy using the non-International System of Units unit Decibel, and is determined by subtracting system losses and adding system gains.... of FM radio station with 50 km range
60 dBm	1 kW = 1000 W	Typical combined radiated RF power of microwave oven Microwave oven A microwave oven, or a microwave, is a kitchen appliance that cookings or heats food by dielectric heating. This is accomplished by using microwave radiation to heat water and other dipole within the food.... elements
50 dBm	100 W	Typical thermal radiation emitted by a human body Black body In physics, a black body is an Physical body that absorbs all electromagnetic radiation that falls on it. No electromagnetic radiation passes through it and none is Reflection ....
40 dBm	10 W
36 dBm	4 W	Typical maximum output power for a Citizens' band radio Citizens' band radio Citizens' Band radio is, in many countries, a system of short-distance radio communications between individuals on a selection of 40 channels within the 27-Hertz band.... station (27 MHz) in many countries
33 dBm	2 W	Maximum output from a UMTS/3G 3G 3G is the third generation of tele standards and technology for mobile networking, superseding 2.5G. It is based on the International Telecommunication Union family of standards under the IMT-2000.... mobile phone (Power class 1 mobiles) Maximum output from a GSM850/900 mobile phone
30 dBm	1 W = 1000 mW	Typical RF leakage from a microwave oven - Maximum output power for DCS 1800 MHz mobile phone Maximum output from a GSM1800/1900 mobile phone
27 dBm	500 mW	Typical cellular phone transmission power Maximum output from a UMTS/3G mobile phone (Power class 2 mobiles)
26 dBm	400 mW
25 dBm	316 mW
24 dBm	250 mW	Maximum output from a UMTS/3G mobile phone (Power class 3 mobiles)
23 dBm	200 mW
22 dBm	160 mW
21 dBm	125 mW	Maximum output from a UMTS/3G mobile phone (Power class 4 mobiles)
20 dBm	100 mW	Bluetooth Bluetooth Bluetooth is a wireless protocol for exchanging data over short distances from fixed and mobile devices, creating personal area networks . It was originally conceived as a wireless alternative to RS232 data cables.... Class 1 radio, 100 m range (maximum output power from unlicensed FM transmitter FM transmitter FM transmitter may refer to:* A transmitter sending out a Frequency modulation signal* An FM transmitter , a very short range device performing the same function... ). Typical wireless router Wireless router A wireless router is a network device that performs the functions of a router but also includes the functions of a wireless access point. It is commonly used to allow access to the Internet or a computer network without the need for a cabled connection.... transmission power.
15 dBm	32 mW	Typical WiFi WIFI WIFI is a radio station broadcasting a Variety radio format. Licensed to Florence, New Jersey, USA. The station is currently owned by Forsythe Broadcasting.... transmission power in laptops.
10 dBm	10 mW
6 dBm	4.0 mW
5 dBm	3.2 mW
4 dBm	2.5 mW	Bluetooth Class 2 radio, 10 m range
3 dBm	2.0 mW	More precisely (to 8 decimal places) 1.9952623 mW
2 dBm	1.6 mW
1 dBm	1.3 mW
0 dBm	1.0 mW = 1000 µW	Bluetooth standard (Class 3) radio, 1 m range
-1 dBm	794 µW
-3 dBm	501 µW
-5 dBm	316 µW
-10 dBm	100 µW	Typical maximum received signal power (−10 to −30 dBm) of wireless network Wireless network Wireless network refers to any type of computer network that is wireless, and is commonly associated with a telecommunications network whose interconnections between Node is implemented without the use of wires....
-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	Typical range (−60 to −80 dBm) of wireless (802.11x) received signal power over a network
-80 dBm	10 pW
-100 dBm	0.1 pW
-111 dBm	0.008 pW = 8 fW	Thermal noise floor Johnson–Nyquist noise Johnson?Nyquist noise is the electronic noise noise generated by the thermal agitation of the charge carriers inside an electrical conductor at equilibrium, which happens regardless of any applied voltage.... for commercial GPS single channel signal bandwidth (2 MHz)
-127.5 dBm	0.178 fW = 178 aW	Typical received signal power from a GPS satellite GPS satellite A GPS satellite is a satellite used by the NAVSTAR Global Positioning System . The first satellite in the system, Navstar 1, was launched February 22, 1978....
-174 dBm	0.004 aW = 4 zW	Thermal noise floor for 1 Hz bandwidth at room temperature (20 °C)
-192.5 dBm	0.056 zW = 56 yW	Thermal noise floor for 1 Hz bandwidth in outer space (4 kelvin Kelvin The kelvin is a Units of measurement of temperature and is one of the seven SI base units. The Kelvin scale is a Thermodynamic temperature scale where absolute zero, the theoretical absence of all thermal energy, is zero .... s)
-8 dBm	0 W	Zero power is not well-expressed in dBm (value is negative infinity)

The signal intensity (power per unit area) can be converted to received signal power by multiplying by the square of the wavelength and dividing by 4p (see Free-space path loss).

In United States Department of Defense

United States Department of Defense

The United States Department of Defense is the federal department charged with coordinating and supervising all agencies and functions of the government relating directly to national security and the Military of the United States....
practice, unweighted

Weighting filter

A weighting filter is used to emphasise or suppress some aspects of a phenomenon compared to others, for measurement or other purposes....
measurement is normally understood, applicable to a certain bandwidth, which must be stated or implied.

In European practice, psophometric weighting

Psophometric weighting

Psophometric weighting refers to any weighting curve used in the measurement of noise. In the field of audio engineering it has a more specific meaning, referring to noise weightings used especially in measuring noise on telecommunications circuits....
may be, as indicated by context, equivalent to dBm0p, which is preferred.

The dBm is not a part of the International System of Units

International System of Units

The International System of Units is the modern form of the metric system and is generally a system devised around the convenience of the number ten....
and therefore is discouraged from use in documents or systems that adhere to SI units (the corresponding SI unit is the watt). However the straight decibel

Decibel

The decibel is a logarithmic units of measurement that expresses the magnitude of a physical quantity relative to a specified or implied reference level....
(dB), being a unitless ratio of two numbers, is perfectly acceptable.

Expression in dBm is typically used for optical and electrical power measurements, not for other types of power (such as thermal). A listing by power levels in watts

Orders of magnitude (power)

This page lists examples of the power in watts produced by various different sources of energy. They are grouped by orders of magnitude, and each section covers three orders of magnitude, or a factor of one thousand....
is available that includes a variety of examples not necessarily related to electrical or optical power.

DBm

Unit conversions

See also

External links