Buy an Ultra High Speed certified cable — the category rated for 48 Gbit/s — and buy the shortest length that reaches.
The two categories that mean something
Premium High Speed is certified for 18 Gbit/s, which covers 4K at 60 Hz. Ultra High Speed is certified for 48 Gbit/s, which covers 4K at 120 Hz and 8K at 60. Both are verifiable certifications with a hologram, not marketing terms.
Why length is the real specification
A passive copper cable carries 48 Gbit/s reliably to roughly three metres — an order of magnitude, not a normative limit, and it varies with construction. Beyond that the honest options are an active cable, which is directional and marked at each end, or an optical one, which goes tens of metres.
The failure people misdiagnose
A picture that works at 60 Hz and drops out at 120, or that flickers and blanks. That is almost always bandwidth, and almost always length. A shorter certified cable fixes it more often than any other change.
What does not matter
The colour, the braid, the price above the certified tier, and the version number printed on the packaging.
Questions people actually ask
Is an expensive cable better?
Past certification, no. A certified Ultra High Speed cable carries 48 Gbit/s, and one that costs five times more carries the same 48 Gbit/s. Braiding, gold plating and thickness are construction and durability, not bandwidth.
My cable says "HDMI 2.1". Is that enough?
It is not a specification. HDMI licensing forbids selling cables by version number precisely because a "2.1" cable can carry any bandwidth at all. The label that means something is "Ultra High Speed", which carries a certification hologram that can be verified in an app.
Last reviewed 4 September 2026