A figure of merit is a quantity used to characterize the performance of a device, system or method, relative to its alternatives. In engineering, figures of merit are often defined for particular materials or devices in order to determine their relative utility for an application. In commerce, such figures are often used as a marketing tool to convince consumers to choose a particular brand.

Examples

• Clock rate
  Clock rate
  The clock rate typically refers to the frequency that a CPU is running at.For example, a crystal oscillator frequency reference typically is synonymous with a fixed sinusoidal waveform, a clock rate is that frequency reference translated by electronic circuitry into a corresponding square wave...
  
   of a CPU
• Calorie
  Calorie
  The calorie is a pre-SI metric unit of energy. It was first defined by Nicolas Clément in 1824 as a unit of heat, entering French and English dictionaries between 1841 and 1867. In most fields its use is archaic, having been replaced by the SI unit of energy, the joule...
  
  s per serving
• Contrast ratio
  Contrast ratio
  The contrast ratio is a property of a display system, defined as the ratio of the luminance of the brightest color to that of the darkest color that the system is capable of producing...
  
   of an LCD
• Frequency response
  Frequency response
  Frequency response is the quantitative measure of the output spectrum of a system or device in response to a stimulus, and is used to characterize the dynamics of the system. It is a measure of magnitude and phase of the output as a function of frequency, in comparison to the input...
  
   of a speaker
  Loudspeaker
  A loudspeaker is an electroacoustic transducer that produces sound in response to an electrical audio signal input. Non-electrical loudspeakers were developed as accessories to telephone systems, but electronic amplification by vacuum tube made loudspeakers more generally useful...
  
  
• Fill factor
  Fill factor
  Fill factor may refer to:*Fill factor , the ratio of maximum obtainable power to the product of the open-circuit voltage and short-circuit current*In vision science, the ratio of view areas to the object visible areas....
  
   of a solar cell
  Solar cell
  A solar cell is a solid state electrical device that converts the energy of light directly into electricity by the photovoltaic effect....
  
  
• Resolution
  Image resolution
  Image resolution is an umbrella term that describes the detail an image holds. The term applies to raster digital images, film images, and other types of images. Higher resolution means more image detail....
  
   of the image sensor
  Image sensor
  An image sensor is a device that converts an optical image into an electronic signal. It is used mostly in digital cameras and other imaging devices...
  
   in a digital camera
  Digital camera
  A digital camera is a camera that takes video or still photographs, or both, digitally by recording images via an electronic image sensor. It is the main device used in the field of digital photography...
  
  
• Detection performance of a sonar
  Sonar
  Sonar is a technique that uses sound propagation to navigate, communicate with or detect other vessels...
  
   system
• Noise figure
  Noise figure
  Noise figure is a measure of degradation of the signal-to-noise ratio , caused by components in a radio frequency signal chain. The noise figure is defined as the ratio of the output noise power of a device to the portion thereof attributable to thermal noise in the input termination at standard...
  
   of a radio receiver
• The thermoelectric
  Thermoelectric effect
  The thermoelectric effect is the direct conversion of temperature differences to electric voltage and vice-versa. A thermoelectric device creates a voltage when there is a different temperature on each side. Conversely, when a voltage is applied to it, it creates a temperature difference...
  
   figure of merit, Z, a material constant proportional to the efficiency of a thermoelectric couple made with the material
• The figure of merit of digital-to-analog converter
  Digital-to-analog converter
  In electronics, a digital-to-analog converter is a device that converts a digital code to an analog signal . An analog-to-digital converter performs the reverse operation...
  
   (DAC) is calculated as (Power dissipation)/((2^ENOB) * Effective Bandwidth) [J/Hz].
• Luminous efficacy
  Luminous efficacy
  Luminous efficacy is a measure of how well a light source produces visible light. It is the ratio of luminous flux to power. Depending on context, the power can be either the radiant flux of the source's output, or it can be the total electric power consumed by the source.Which sense of the term is...
  
   of lighting
  Lighting
  Lighting or illumination is the deliberate application of light to achieve some practical or aesthetic effect. Lighting includes the use of both artificial light sources such as lamps and light fixtures, as well as natural illumination by capturing daylight...
  
  
• Battery life of a laptop computer

Benchmark

Benchmark (computing)

In computing, a benchmark is the act of running a computer program, a set of programs, or other operations, in order to assess the relative performance of an object, normally by running a number of standard tests and trials against it...

s are synthetic figures of merit that summarize the speed of computers in performing various typical tasks. Benchmarks designed by a manufacturer generally rate the manufacturer's products more favorably than benchmarks designed by others or by independent benchmarkers.

Modulation Systems

In modulation systems for communication, figure of merit of a device means the ratio of output Signal to Noise Ratio to the input Signal to Noise Ratio.

Amplitude modulation

Figure of merit for Amplitude modulation is given by

Figure of merit for DSB-SC receiver or that of an SSB modulation is always unity. Therefore noise performance of AM receiver is inferior to that of a DSB-SC receiver or an SSB receiver.

Frequency modulation

Figure of merit for Frequency modulation is given by

Deception

The precision and verifiability of numbers sometimes make them a more effective sales tool than vague and non numeric descriptions such as "state of the art" or "leaves the others in the dust". When used in deceptive advertising, the deception lies more in the question of relevance rather than truth since the number quoted as a figure of merit may not be enough to determine performance when comparing products. For example, when purchasing a laptop a consumer could choose based on the capacity of its hard drive. The RPM

Revolutions per minute

Revolutions per minute is a measure of the frequency of a rotation. It annotates the number of full rotations completed in one minute around a fixed axis...

, buffer

Disk buffer

In computer storage, disk buffer is the embedded memory in a hard drive acting as a buffer between the rest of the computer and the physical hard disk platter that is used for storage...

, and seek times may not be noted, but significantly affect performance.

Some figures such as Peak Music Power are used in selling consumer merchandise and have the principal merit of yielding high numbers that can impress people who don't know what the numbers mean. Other figures such as Specific Fuel Consumption are addressed to engineers and other studious buyers whom the sellers dare not mislead.

Another example is the megapixel count of a digital camera

Digital camera

A digital camera is a camera that takes video or still photographs, or both, digitally by recording images via an electronic image sensor. It is the main device used in the field of digital photography...

. A consumer unaware that the number of pixels on a sensor is only one factor in the quality of the image that is captured may, for example, buy a camera with more pixels squeezed onto a small image sensor

Image sensor

An image sensor is a device that converts an optical image into an electronic signal. It is used mostly in digital cameras and other imaging devices...

, thus losing quality to small pixels.

Makers of cheap, consumer-market telescopes

Optical telescope

An optical telescope is a telescope which is used to gather and focus light mainly from the visible part of the electromagnetic spectrum for directly viewing a magnified image for making a photograph, or collecting data through electronic image sensors....

 often tout the magnification power of their products, sidestepping the fact that aperture

Aperture

In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture of an optical system is the opening that determines the cone angle of a bundle of rays that come to a focus in the image plane. The aperture determines how collimated the admitted rays are,...

, optical quality, and the type and quality of the telescope's mount are of more importance in obtaining a quality image.