4K resolution is a generic term to refer to any horizontal display resolution of approximately 4,000 pixels. Several different 4K resolutions have been standardized by various organizations, including for digital cinematography, and for digital television.

The terms and are used more widely in marketing than (cf. ), and typically refer to motion pictures and video. Some digital camera vendors have used the term for still photographs, making it appear like an especially high resolution even though pixels equal approximately 8.3 megapixels, which is not considered to be especially high for still photographs. 4K resolution is approximately 8 million pixels, which is 4 times as many as 1080p. 4K television market share increased as prices fell dramatically throughout 2013 and 2014.

Standards DCI Digital Cinema System Specification

In 2005, Digital Cinema Initiatives (DCI), a prominent standards organization in the cinema industry, published the Digital Cinema System Specification. This specification establishes standardized 2K and 4K container formats for digital cinema production, with resolutions of and respectively. The resolution of the video content inside follows the SMPTE ST 429 standard, which establishes the following resolutions for a 4K distribution: (full frame, or aspect ratio) (flat crop, aspect ratio) (CinemaScope crop, aspect ratio) 2K distributions can have a frame rate of either 24 or 48FPS, while 4K distributions must have a frame rate of 24FPS.

Some articles claim that the terms and were coined by DCI and refer exclusively to the 2K and 4K formats defined in the DCI standard. However, usage of these terms in the cinema industry predates the publication of the DCI standard, and they are generally understood as casual terms for any resolution approximately 2000 or 4000 pixels in width, rather than names for specific standard resolutions.

SMPTE UHDTV standard In 2007, the Society of Motion Picture and Television Engineers published SMPTE ST 2036-1, which defines parameters for two UHDTV systems called and . The standard defines the following characteristics for these systems: A resolution of (UHDTV1) or (UHDTV2) Square () pixels, for an overall image aspect ratio of A framerate of 23.976, 24, 25, 29.97, 30, 50, 59.94, 60, 100, 119.88, or 120Hz with progressive scan RGB, 4:4:4, 4:2:2, or 4:2:0 pixel encoding 10bpc () or 12bpc () color depth Colorimetry characteristics as defined in the standard, including color primaries, quantization parameters, and the electro-optical transfer function. These are the same characteristics later standardized in ITU-R BT.2020. UHDTV1 systems are permitted to use BT.709 color primaries up to 60Hz.

ITU-R UHDTV standard In 2012, the International Telecommunication Union, Radiocommunication Sector published Recommendation BT.2020, also known as the Ultra High Definition Television (UHDTV) standard. It adopts the same image parameters defined in SMPTE ST 2036–1.

Although the UHDTV standard does not define any official names for the formats it defines, ITU typically uses the terms , , or to refer to the system in public announcements and press releases ( for the system). In some of ITU's other standards documents, the terms and are used as shorthand.

CEA Ultra HD In October 2012, the Consumer Electronics Association (CEA) announced its definition of the term (or ) for use with marketing consumer display devices. CEA defines an product as a TV, monitor, or projector with the following characteristics: A resolution of or larger An aspect ratio of 1.1 () or wider Support for color depth of 8bpc () or higher At least one HDMI input capable of supporting at 24, 30, and 60Hz progressive scan (though not necessarily with RGB or 4:4:4 color), and HDCP2.2 Capable of processing images according to the color space defined in ITU-R BT.709 Capable of upscaling HD content (i.e., 720p or 1080p)

The CEA definition does allow manufacturers to use other terms—such as —alongside the Ultra HD logo. Since the resolution in CEA's definition is only a minimum requirement, displays with higher resolutions such as or also qualify as Ultra HD displays, provided they meet the other requirements.

2160p resolution Some 4K resolutions, like , are often casually referred to as . This name follows from the previous naming convention used by HDTV and SDTV formats, which refer to a format by the number of pixels or lines along the vertical axis (such as for progressive scan, or for the 480-line interlaced SDTV formats) rather than the horizontal pixel count (≈4000 or 4K for ).

The term could be applied to any format with a height of 2160 pixels, but it is most commonly used in reference to the 4K UHDTV resolution of due to its association with the well-known 720p and 1080p HDTV formats. Although is both a 4K resolution and a 2160p resolution, these terms cannot always be used interchangeably since not all 4K resolutions are 2160 pixels tall, and not all 2160p resolutions are ≈4000 pixels wide. However, some companies have begun using the term 4K to describe devices with support for a 2160p resolution, even if it is not close to 4000 pixels wide. For example, many 4K dash cams only support a resolution of (); although this is a 2160p resolution, it is not a 4K resolution. Conversely, Samsung released a () TV, but marketed it as a 4K TV despite its 5K-class resolution.

M+ or RGBW TV controversy In 2015, LG Display announced the implementation of a new technology called M+, which is the addition of white subpixels along with the regular RGB dots in their IPS panel technology. The media and internet users later called this "RGBW" TVs because of the white sub pixel.

Most of the new M+ technology was employed on 4K TV sets, which led to a controversy after tests showed that the addition of a white subpixel replacing the traditional RGB structure would reduce the resolution by around 25%. After tests done by Intertek in which the technical aspects of LG M+ TVs were analyzed and they concluded that "the addressable resolution display is 2,880 X 2,160 for each red, green, blue", in other words, the LG TVs were technically 2.8K as it became known in the controversy. Although LG Display has developed this technology for use in notebook display, outdoor and smartphones, it is more popular in the TV market due to the supposed 4K UHD marketed resolution but still being incapable of achieving true 4K UHD resolution as defined by the CTA as 3840x2160 active pixels with 8-bit per color. This negatively impacts the rendering of text, making it a bit fuzzier, which is especially noticeable when a TV is used as a PC monitor.

CinemaWide 4K In 2019, Sony was granted the CinemaWide trademark by the European Union Intellectual Property Office (EUIPO), in which the trademark covers 'Class 9' electronic devices, including smartphones. According to Sony and SID, the standard defines a CinemaWide 4K product with the following characteristics: A resolution of or larger An aspect ratio of Capable of playing back 4K resolution video (2160p) in an aspect ratio of Capable of upscaling non-4K content (i.e. 720p / 1080p)

Sony Xperia smartphones are the most widely known products that equipped with CinemaWide 4K display, such as Xperia 1, Xperia 1 II, Xperia 1 III, Xperia 1 IV and Xperia 1 V.

Adoption Video sharing website YouTube and the television industry have adopted 38402160 as their 4K standard. , 4K content from major broadcasters remained limited. By late 2014, 4K content was becoming more widely available online, including on Apple TV, YouTube, Netflix, Hulu, and Amazon Prime Video.

By 2013, some UHDTV models were available to general consumers in the range of US$600. , prices on smaller computer and television panels had dropped below US$400.

ATSC On March 26, 2013, the Advanced Television Systems Committee announced new proposals of a new standard called ATSC 3.0 which would implement UHD broadcasts at resolutions of up to or . The standard would also include framerates of up to 120Hz, HEVC encoding, wide color gamut, as well as high dynamic range.

DVB In 2014, the Digital Video Broadcasting Project released a new set of standards intended to guide the implementation of high-resolution content in broadcast television. Dubbed , it establishes two standards, known as (for 4K content) and (for 8K content). These standards use resolutions of 38402160 and 76804320 respectively, with framerates of up to 60Hz, color depth up to 10bpc (30bit/px), and HEVC encoding for transmission. DVB is currently focusing on the implementation of the UHD-1 standard.

DVB finalized in 2016, with the introduction of service by broadcasters expected in 2017. UHD-1 Phase 2 adds features such as high dynamic range (using HLG and PQ at 10 or 12 bits), wide color gamut (BT. 2020/2100 colorimetry), and high frame rate (up to 120Hz).

Video streaming As of February 2025, both YouTube and Vimeo support high-resolution video uploads, with maximum resolutions of 4096 × 2304 pixels (approximately 9.4 megapixels) and 4096 × 2160 pixels (approximately 8.8 megapixels), respectively. The growing availability of 4K content across streaming platforms like Netflix, Amazon Prime Video, and YouTube has made it more accessible to consumers. Vimeo's 4K content is currently limited to mostly nature documentaries and tech coverage.

High Efficiency Video Coding (HEVC or H.265) facilitates streaming of 4K content at bitrates between 20 and , offering efficient compression without significant quality loss.

In January 2014, Naughty America launched the first adult video service streaming in 4K.

In February 2025, Super Bowl LIX was broadcast in 4K resolution with Dolby Vision HDR and Dolby Atmos sound for the first time. Fox aired the game, and it was also available for free streaming in 4K on Tubi, marking a significant milestone in sports broadcasting.

Mobile phone cameras

The first mobile phones to be able to record at 2160p () were released in late 2013, including the Samsung Galaxy Note 3, which is able to record 2160p at 30 frames per second.

In the year 2014, the OnePlus One was released with the option to record DCI 4K () at 24 frames per second, as well as LG G3 and Samsung Galaxy Note 4 with optical image stabilization.

In the year 2015, Apple announced the iPhone 6s was released with the 12megapixel camera that has the option to record 4K at 25 or 30 frames per second.

In the years 2017 and 2018, mobile phone chipsets reached sufficient processing power that mobile phone vendors started releasing mobile phones that allow recording 2160p footage at 60 frames per second for a smoother and more realistic appearance. Personal computers iMac with Retina Display (2014) is one of the earliest computers that utilise 4K widescreen.

History

In 1981, the NEC μPD7220 computer graphics processor supported monochrome resolutions up to 4096×1024p (progressive scan) or 4096×2048i (interlaced). In 1984, Hitachi's ARTC HD63484 graphics processor supported monochrome resolutions up to 4096×2048p (progressive scan) or 4096×4096i (interlaced), targeted at the bit-mapped desktop publishing market.

In 2000, JVC introduced the first 4K digital cinema video projector using D-ILA technology. The first commercially available 4K camera for cinematographic purposes was the Dalsa Origin, released in 2003. Sony began offering 4K digital cinema projectors in 2004. 4K digital projectors were introduced to movie theaters in 2005, but most theaters continued using analog movie projectors until 4K digital projectors eventually replaced them by 2011.

4K streaming technology was developed during the mid-to-late 2000s by several research groups in universities around the world, such as University of California, San Diego, CALIT2, Keio University and Naval Postgraduate School. They realized several demonstrations in venues such as IGrid in 2004 and CineGrid.