Quick answer: A 4K60 television needs 18 Gbit/s, which a Premium High Speed cable delivers for AUD 20 to 35. Only 4K120, 8K or 4K60 at 4:4:4 with 10 bit colour needs 48 Gbit/s and an Ultra High Speed cable at AUD 35 to 60. Streaming services send 4K at 4:2:0, so the extra bandwidth buys nothing for Netflix, but it does matter for a gaming PC or a console. Check the port, the source and the chroma setting, in that order.
The number on the cable packet and the number in the television menu rarely agree, and that mismatch is where most 4K buying goes wrong. Bandwidth is arithmetic: pixels, refresh rate, colour depth and chroma sampling multiply into a figure that either fits a cable or does not. Run that sum before you shop and the choice narrows to one tier, or two at most.
The two bandwidth tiers that matter
18 Gbit/s and what it covers
18 Gbit/s carries 4K60 at 8 bit with 4:4:4, or 4K60 at 10 bit with 4:2:2, and it covers every free to air, Foxtel and streaming service in Australia. Premium High Speed certification is the label to look for. That tier also handles 1080p120 and 1440p at high refresh, which is why it still suits most desktop monitors.
48 Gbit/s and what it adds
48 Gbit/s covers 4K120 at 10 bit with 4:4:4, and 8K60 with compression. It exists for consoles, graphics cards and the small number of 8K panels sold here. If nothing in the house outputs above 4K60, the extra headroom is dormant, though it does buy some insurance for the next device you plug in.
4:4:4, 4:2:2 and 4:2:0 in practice
Chroma subsampling and text
4:4:4 sends full colour information for every pixel. 4:2:0 sends a quarter of it and relies on the eye to fill the gap. On film content the difference is invisible. On a desktop with fine text, 4:2:0 produces colour fringing on letters, which is why a PC should run 4:4:4 and a television fed by a streaming stick does not need to.
| Format | Pixels | Chroma | Bit depth | Gbit/s |
|---|
| 4K60 | 3840 x 2160 | 4:2:0 | 8 bit | 8.9 |
| 4K60 | 3840 x 2160 | 4:2:2 | 10 bit | 14.9 |
| 4K60 | 3840 x 2160 | 4:4:4 | 8 bit | 17.8 |
| 4K120 | 3840 x 2160 | 4:2:2 | 10 bit | 29.7 |
| 4K120 | 3840 x 2160 | 4:4:4 | 10 bit | 44.6 |
HDR adds overhead
HDR10 carries static metadata in the blanking interval and costs almost nothing in bandwidth, but the 10 bit colour depth it usually comes with adds 25 per cent over 8 bit. Dolby Vision adds dynamic metadata per scene. If the display and the source both support it, check that the cable still passes 4K60 at 10 bit rather than falling back silently to 8 bit.
Which cable a 4K TV actually needs
Streaming sticks and consoles
A streaming stick in the port needs no cable at all, and a set top box needs 18 Gbit/s. A current console will ask for 4K120 on some titles, so fit a 48 Gbit/s cable on that input and leave the others on 18 Gbit/s stock. Mixing the two is fine, and it keeps the cost sensible across four ports.
PCs and desktop use
A desktop at 4K60 with 4:4:4 sits just under the 18 Gbit/s ceiling, so a certified Premium High Speed cable at 2 m is enough. Add HDR at 10 bit and a 144 Hz panel and the requirement jumps to 48 Gbit/s. Long desk runs past 3 m need an active HDMI cable rather than a thicker passive cable, and a HDMI cable extender is the practical answer when the PC sits in another room.
Proving the link before you blame the TV
Patterns and error counts
Test with a moving pattern rather than a menu. Sparkles that appear in dark areas, a line of coloured pixels along one edge, or a blank flash every few minutes all point at the link, not the panel. If the same cable passes at 1080p and fails at 4K60, the bandwidth budget is the problem. An HDMI cable tester confirms which lane is failing before you buy a replacement.
Send the display model, the source model and the cable length to zongcarrie@zh-zong.com or call +86 13543026126 and we will confirm whether 18 or 48 Gbit/s is the right tier and quote certified stock in AUD. A five minute cable check at the quote stage is cheaper than a second cable and a return trip.
Practical scenarios
- Situation: A Gold Coast townhouse with a 4K60 panel, a Fetch box and a soundbar. What to do: Use 18 Gbit/s cables on both legs.
- Situation: A North Sydney office with 4K monitors on 3 m desk runs. What to do: Certified 2 m cables, 4:4:4 in the driver, active past 3 m.
- Situation: A Western Sydney warehouse with a 4K player 20 m from the screen. What to do: Use an extender over Cat6 and set 4:2:0.
- Situation: A Brunswick house with a gaming PC in the study and a 4K120 panel. What to do: Fit a 48 Gbit/s active cable for the long leg.
FAQ
Do 4K streaming services need a 48 Gbit/s cable?
No. Streaming services send 4K at 4:2:0 with 8 or 10 bit colour, which fits inside 18 Gbit/s with room to spare. A certified Premium High Speed cable is enough. The higher tier matters for consoles, PCs and disc players, not for apps on a television.
Why does 4K look soft compared with the shop display?
Shop displays run a loop at the panel native resolution with sharpening applied. At home the source may be 1080p, the picture mode may be set to standard, and overscan may be on. Check the source output first, then the picture mode, then the cable.
Can a cable cause colour banding?
A marginal cable causes sparkles, dropouts or a blank screen rather than banding. Banding comes from 8 bit processing, heavy compression or a picture mode that crushes gradients. Test the same source on a different input before spending money on a cable.
