Form factor is a hardware

design A design is the concept or proposal for an object, process, or system. The word ''design'' refers to something that is or has been intentionally created by a thinking agent, and is sometimes used to refer to the inherent nature of something ...

aspect that defines and prescribes the size, shape, and other physical

specifications A specification often refers to a set of documented requirements to be satisfied by a material, design, product, or service. A specification is often a type of technical standard. There are different types of technical or engineering specificati ...

of components, particularly in

electronics Electronics is a scientific and engineering discipline that studies and applies the principles of physics to design, create, and operate devices that manipulate electrons and other Electric charge, electrically charged particles. It is a subfield ...

. A form factor may represent a broad class of similarly sized components, or it may prescribe a specific standard. It may also define an entire system, as in a computer form factor.

Evolution and standardization

As electronic hardware has become smaller following

Moore's law Moore's law is the observation that the Transistor count, number of transistors in an integrated circuit (IC) doubles about every two years. Moore's law is an observation and Forecasting, projection of a historical trend. Rather than a law of ...

and related patterns, ever-smaller form factors have become feasible. Specific technological advances, such as

PCI Express PCI Express (Peripheral Component Interconnect Express), officially abbreviated as PCIe, is a high-speed standard used to connect hardware components inside computers. It is designed to replace older expansion bus standards such as Peripher ...

, have had a significant design impact, though form factors have historically evolved slower than individual components.

Standardization Standardization (American English) or standardisation (British English) is the process of implementing and developing technical standards based on the consensus of different parties that include firms, users, interest groups, standards organiza ...

of form factors is vital for hardware compatibility between different manufacturers.

Trade-offs

Smaller form factors may offer more efficient use of limited space, greater flexibility in the placement of components within a larger assembly, reduced use of material, and greater ease of transportation and use. However, smaller form factors typically incur greater costs in the

manufacturing Manufacturing is the creation or production of goods with the help of equipment, labor, machines, tools, and chemical or biological processing or formulation. It is the essence of the secondary sector of the economy. The term may refer ...

, and

maintenance The technical meaning of maintenance involves functional checks, servicing, repairing or replacing of necessary devices, equipment, machinery, building infrastructure and supporting utilities in industrial, business, and residential installa ...

phases of the engineering lifecycle, and do not allow the same expansion options as larger form factors. In particular, the design of smaller form-factor computers and network equipment must entail careful consideration of

cooling Cooling is removal of heat, usually resulting in a lower temperature and/or Phase transition, phase change. Temperature lowering achieved by any other means may also be called cooling. The Heat transfer, transfer of Internal energy, thermal energ ...

End-user In product development, an end user (sometimes end-user) is a person who ultimately uses or is intended to ultimately use a product. The end user stands in contrast to users who support or maintain the product, such as sysops, system administrato ...

maintenance and repair of small form-factor electronic devices such as mobile phones is often not possible, and may be discouraged by

warranty In law, a warranty is an expressed or implied promise or assurance of some kind. The term's meaning varies across legal subjects. In property law, it refers to a covenant by the grantor of a deed. In insurance law, it refers to a promise by the ...

voiding Urination is the release of urine from the bladder through the urethra in placental mammals, or through the cloaca in other vertebrates. It is the urinary system's form of excretion. It is also known medically as micturition, voiding, ures ...

clauses; such devices require professional servicing—or simply replacement—when they fail.

Examples

Computer form factors comprise a number of specific industry standards for

motherboard A motherboard, also called a mainboard, a system board, a logic board, and informally a mobo (see #Nomenclature, "Nomenclature" section), is the main printed circuit board (PCB) in general-purpose computers and other expandable systems. It ho ...

s, specifying dimensions,

power supplies A power supply is an electrical device that supplies electric power to an electrical load. The main purpose of a power supply is to convert electric current from a source to the correct voltage, current, and frequency to power the load. As a r ...

, placement of mounting holes and

ports Ports collections (or ports trees, or just ports) are the sets of makefiles and Patch (Unix), patches provided by the BSD-based operating systems, FreeBSD, NetBSD, and OpenBSD, as a simple method of installing software or creating binary packages. T ...

, and other parameters. Other types of form factors for computers include: *

Small form factor Small form factor (SFF) is a classification of desktop computers and for some of their components, chassis and motherboard, to indicate that they are designed in accordance with one of several standardized form factors intended to minimize the vo ...

(SFF), a more loosely defined set of standards that may refer to both motherboards and

computer case A computer case, also known as a computer chassis, is the enclosure that contains most of the hardware of a personal computer. The components housed inside the case (such as the CPU, motherboard, memory, mass storage devices, power supply unit ...

s. SFF devices include mini-towers and

home theater PC A home theater PC (HTPC) or media center computer is a technological convergence, convergent device that combines some or all the capabilities of a personal computer with a software application that focuses on video, photo, audio playback, and ...

s. *

Pizza box form factor In computing, a pizza box is a style of case design for desktop computers or network switches. Pizza box cases tend to be wide and flat, normally in height, resembling pizza delivery boxes and thus the name. This is in contrast to a tower sy ...

, a wide, flat case form factor used for computers and network switches; often sized for installation in a

19-inch rack A 19-inch rack is a standardized frame or enclosure for mounting multiple electronic equipment modules. Each module has a front panel that is wide. The 19 inch dimension includes the edges or ''ears'' that protrude from each side of the ...

. *

All-in-one PC An all-in-one computer (also called an AIO or all-in-one PC) is a type of personal computer that integrates the computer components, such as the CPU, monitor, and speakers, into a single unit. It occupies a smaller footprint than a desktop co ...

* "Lunchbox"

portable computer A portable computer is a computer designed to be easily moved from one place to another, as opposed to those designed to remain stationary at a single location such as desktops and workstations. These computers usually include a display a ...

Components

* Hard disk drive form factors, the physical dimensions of a computer hard drive * Hard disk enclosure form factor, the physical dimensions of a computer hard drive enclosure *

Motherboard form factor In computing, the motherboard form factor is the specification of a motherboard – the dimensions, power supply type, location of mounting holes, number of ports on the back panel, etc. Specifically, in the IBM PC compatible industry, standard ...

, the physical dimensions of a computer motherboard * Memory module form factors

Mobile form factors

Laptop A laptop computer or notebook computer, also known as a laptop or notebook, is a small, portable personal computer (PC). Laptops typically have a Clamshell design, clamshell form factor (design), form factor with a flat-panel computer scree ...

notebook A notebook (also known as a notepad, writing pad, drawing pad, or legal pad) is a book or stack of paper pages that are often ruled and used for purposes such as note-taking, journaling or other writing, drawing, or scrapbooking and more. ...

, a form of portable computer with a

clamshell design Clamshell design is a form factor commonly used in the design of electronic devices and other manufactured objects. It is inspired by the morphology of the clam. The form factor has been applied to handheld game consoles, mobile phones (wh ...

. *

Subnotebook Subnotebook, also called ultraportable, superportable, handtop, mini notebook or mini laptop, is a type of laptop computer that is smaller and lighter than a typical notebook-sized laptop. Types and sizes As typical laptop sizes have decreas ...

ultra-mobile PC An ultra-mobile PC, or ultra-mobile personal computer (UMPC), is a miniature version of a pen computer, a class of laptop whose specifications were launched by Microsoft and Intel in Spring 2006. Sony had already made a first attempt in this ...

netbook A netbook is a small-sized laptop computer; they were primarily sold from 2007 until around 2013, designed mostly as a means of accessing the Internet and being significantly less expensive than regular-sized laptops. At their inception in l ...

, and

tablet computer A tablet computer, commonly shortened to tablet, is a mobile device, typically with a mobile operating system and touchscreen display processing circuitry, and a rechargeable battery in a single, thin and flat package. Tablets, being computers ...

, various form factors for devices that are smaller and often cheaper than a typical notebook. *

Mobile phone A mobile phone or cell phone is a portable telephone that allows users to make and receive calls over a radio frequency link while moving within a designated telephone service area, unlike fixed-location phones ( landline phones). This rad ...

, including a wide range of sizes and layouts. Broad categories of form factors include bars,

flip phones Clamshell design is a form factor (design), form factor commonly used in the design of electronic devices and other manufactured objects. It is inspired by the Morphology (biology), morphology of the clam. The form factor has been applied to ha ...

, and sliders, with many subtypes and variations. Also include

phablets A phablet (, ) is a mobile device combining or straddling the size formats of smartphones and Tablet computer, tablets. The word is a blend word of ''phone'' and ''tablet''. The term was largely unused by the late 2010s, since average phone sizes ...

(small tablets) and industrial handheld devices. *

Stick PC A stick PC or PC on a stick is a single-board computer in a small elongated casing resembling a stick, that can usually be plugged directly (without an HDMI cable) into an HDMI video port. A stick PC is a device which has independent CPUs or proc ...

, a

single-board computer A single-board computer (SBC) is a complete computer built on a single circuit board, with microprocessor(s), memory, input/output (I/O) and other features required of a functional computer. Single-board computers are commonly made as demonst ...

in a small elongated casing resembling a stick

Notes

References

{{reflist Design Electronic design Industrial design Packaging Broad-concept articles