What Is HDMI?

HDMI, short for High-Definition Multimedia Interface, is a digital interface that sends uncompressed video and audio from a source, such as a computer, media player or camera, to a display or receiver over a single cable. A group of consumer electronics makers including Hitachi, Panasonic, Philips, Sony and Toshiba published the first specification in December 2002. Today HDMI Licensing Administrator licenses the standard and the HDMI Forum develops new versions.

HDMI grew out of DVI, the digital PC monitor interface, and uses the same signalling for video up to HDMI 2.0. That is why a passive cable can join a DVI-D output to an HDMI input. HDMI added audio, a smaller connector and consumer features, and it became the default connection on TVs, projectors and most monitors.

An HDMI link is more than a video wire. Several separate channels share the 19 pins of the standard connector.

HDMI cables are not sorted by version number. HDMI Licensing Administrator certifies cables by the bandwidth they are tested to carry, and the label on the packaging tells you which formats will run reliably. A cable rated for a higher bandwidth works with every older device.

Cables with an Ethernet channel add the words “with Ethernet” to the name, and an automotive grade exists for in-vehicle wiring. The plug can be the full-size Type A, the smaller Mini HDMI (Type C) found on cameras and some boards, the Micro HDMI (Type D) used on small devices, or the locking Type E automotive connector.

The version number describes what the ports on a device support, not the cable. Each version raised the bandwidth or added features.

• HDMI 1.4 (2009) runs at up to 10.2 Gb/s, which carries 4K at 30 Hz, and added ARC and an Ethernet channel.
• HDMI 2.0 (2013) raised the rate to 18 Gb/s for 4K at 60 Hz, and its 2.0a and 2.0b updates added HDR.
• HDMI 2.1 (2017) moved to a new signalling method called FRL at up to 48 Gb/s, for 4K at 120 Hz and 8K at 60 Hz with compression, and added eARC and variable refresh rate.
• HDMI 2.2, published in 2025, doubles the rate again to around 96 Gb/s.

A link runs at the highest version that the source, the display and the cable all support. Our comparison of HDMI 2.0 vs HDMI 1.4 covers the older step in detail.

The HDMI specification does not set a maximum length. It sets a signal quality the cable must meet, so the practical length falls as the data rate rises. A good passive cable typically carries 1080p reliably to around 10 to 15 m, while 4K at 60 Hz is usually safe to around 5 m, and 48 Gb/s HDMI 2.1 links are shorter still.

For longer runs there are three common answers. Active and optical HDMI cables boost or convert the signal inside the cable and reach tens of metres. HDMI video extenders send the signal over Cat6 or fibre and rebuild it at the far end. For runs of 100 m or more on coax, broadcast and industrial systems often convert to SDI.

HDMI is the most common display output on embedded computers and signage players because almost every monitor and TV accepts it. Its main weakness in industry is the plug: a standard HDMI connector is held only by friction, so systems on vehicles or vibrating machines usually add a retention clip, a screw-lock cable or a locking DisplayPort output instead. Our guide to how DisplayPort compares with HDMI covers that choice.

Our digital signage players drive up to four 4K screens over HDMI from one compact system. Going the other way, HDMI capture cards bring the output of cameras, medical scopes and operator consoles into a computer for recording or AI analysis.

We fit the graphics outputs, HDMI capture cards and extenders each system needs as standard, and check every display and capture path before the system ships.