Ultra High Speed HDMI Cable Ultra High Speed HDMI Cable (48Gbps)

What the Ultra High Speed HDMI Cable is

The Ultra High Speed HDMI Cable was introduced in the HDMI 2.1 specification and entered the market in 2020. HDMI.org says it suits systems that need up to 48 Gbps of bandwidth. The HDMI Forum introduced the program in January 2020, calling it the first cable the Forum defined and a Category 3 cable in HDMI 2.1a. The Forum describes it as the only cable that complies with specifications designed to ensure support for all HDMI 2.1a features, including uncompressed 8K at 60 Hz and 4K at 120 Hz. That feature list runs through Fixed Rate Link signaling, dynamic HDR, source-based tone mapping, eARC, ALLM, VRR, QFT, QMS and HDMI Cable Power. See fixed rate link.

Where it sits in the cable ladder

HDMI.org lists the tiers by what they are designed to carry. A Standard cable is tested for 1080i or 720p. A High Speed cable handles 1080p and beyond with up to 10.2 Gbps, including 4K at 30 Hz. A Premium High Speed cable is certified for 4K60 with HDR at up to 18 Gbps. The Ultra High Speed cable covers up to 48 Gbps with 8K60 and 4K120. The Ultra96 cable, introduced with HDMI 2.2, carries up to 96 Gbps and supports uncompressed full-chroma formats such as 8K60 4:4:4 and 4K240 4:4:4 at 10-bit and 12-bit color. Going from Premium High Speed to Ultra High Speed multiplies the ceiling by 2.67 (48 / 18), and Ultra96 doubles it again. See Ultra96 HDMI cable and HDMI 2.1 bandwidth tiers.

How certification works

HDMI LA's program summary lists six requirements. Every Ultra High Speed cable must be tested and certified to the HDMI 2.1a Compliance Test Specification for Category 3 cables, only at an HDMI Forum Authorized Test Center, with every length of every cable tested individually. Each certified cable is registered for verification, each package must show the Ultra High Speed label, and the program continues verification across the product's life. The cable is tested for signal quality at the full 48 Gbps, for low EMI, and for FRL signaling. The low-EMI test exists to reduce the possibility of interference with wireless networks, streaming media players, Bluetooth devices and mobile phones, and the program summary says the cables exceed the requirements of the latest international EMI standards.

HDMI LA also audits after launch. It buys cables in stores and online marketplaces and sends them to Forum test centers; a failing model gets a chance to correct manufacturing issues or can order no further labels, and a passing one gets a letter and an audit-pass result when its label is scanned. Labels scan with standard QR apps, and the Forum notes the HDMI Cable Certification app on Apple and Google stores. The official cable name must also appear on the jacket itself.

What 48 Gbps covers and what does not need it

The HDMI Forum says certification ensures Ultra High Speed cables support 4K and 8K video, HDR, VRR, eARC and all other HDMI 2.1a features. A cable only matters when something on both ends uses that bandwidth. eARC itself is a good example: HDMI.org says either a Premium High Speed or an Ultra High Speed cable provides the best audio, so choose by the video your system needs. See eARC vs ARC. As arithmetic, 4K at 120 Hz with 10-bit RGB needs 3840 x 2160 x 120 x 30 = 29.86 Gbps of active pixel data, far above the 18 Gbps Premium High Speed ceiling and inside the 48 Gbps Ultra High Speed one, which is why only that tier is certified for it. The cable also cannot upgrade a port. HDMI.org says support for each HDMI 2.1 feature is optional, so a TV or console labeled HDMI 2.1 may not use 48 Gbps at all.

Real examples and length

Certified cables are widely sold. StarTech's HDMI21-CBL-8K60-10F is a 10 ft (3 m) cable listed as certified Ultra High Speed with up to 48 Gbps, 8K at 60 Hz and 4K at 120 Hz, a flexible TPE jacket and a 30 mm minimum bend radius. Length is where the class gets difficult. HDMI.org says the Ultra High Speed requirements in cables longer than a few meters are likely met only with powered, active electronics, and that every length is certified on its own, so a certified 3 m model says nothing about a longer cable of the same brand. For long runs see HDMI cable length limits, active vs passive HDMI cables and fiber optic HDMI cables.

The specification is broader than the living-room version. HDMI LA's program summary says initial certification covers Type A connectors, while the specification also covers Types C and D, and that wire, passive, active and converter cable assemblies are all supported by HDMI 2.1a. Wire is the common case in a home theater; active and optical assemblies are how the class reaches past a few meters.

Common confusions

"HDMI 2.1 cable" is a retail phrase, not an official name; the certified name is Ultra High Speed HDMI Cable, and it is required on the jacket and package. A product page that says "8K" or "48Gbps" is a claim until the label scans to the right brand, model and length. HDMI.org warns that some cables are counterfeits. Ports and cables are certified separately, so a certified cable in a TMDS-only port still runs at that port's lower bandwidth. Read the HDMI cable guide for picks, the PS5 Pro 120Hz TV guide for console setups, and use the HDMI cable tool to match tier to equipment.