Internet speed for 4K TV: how many Mbps per screen?

To watch in 4K, you need between 15 and 25 Mbps per screen. Almost every Belgian bundle gives six times that on paper. The problem lies elsewhere: at some operators, the television on the set-top box draws on the same bandwidth as Netflix, and your real line is not the one in the contract. Here is how to count, screen by screen.

How many Mbps do you need to watch TV in 4K?

15 Mbps at the very least, 25 Mbps to be comfortable.

Each platform publishes its own figure, and they differ. Netflix asks for 15 Mbps for Ultra HD on its help page on recommended speeds, consulted on 21 October 2026. YouTube asks for 20 in its system requirements. Disney+ recommends 25 Mbps. The gap comes from compression: each service encodes its videos its own way, and the one that compresses most asks for least.

These figures are sustained speeds. A 300 Mbps peak on a speed test is worth nothing if the line drops back to 12 during the film.

Three conditions come on top of speed, and they block 4K more often than speed does. The plan first: at Netflix, only the Premium plan streams in 4K. The television next, which must decode the compression format used. And the source: a channel broadcast in HD stays in HD, even on a 4K screen hooked up to fibre.

What speed for two or three screens at once?

Add them up, then keep a quarter as headroom.

The sum is simple, which is why people skip it. A household of four on a Sunday evening: the living room watches a film in 4K, a teenager watches YouTube in Full HD in their bedroom, someone is on a video call, and the kitchen phone is updating its apps. That makes 15 + 5 + 3 + a few Mbps, roughly 30 Mbps that must get through at the same time, before counting the set-top box's television.

The right-hand column is the one to compare with your measured speed. Not with the speed printed in the brochure.

Does your operator's TV run through your internet bandwidth?

It depends on the box, and nobody tells you when you sign up.

In Belgium, two techniques coexist. The coaxial cable carries channels on separate frequencies: your Netflix film and the evening news on La Une do not fight for the same space. Internet television, IPTV (Internet Protocol Television), sends each channel through your connection instead, like any other video. The difference between the two is set out in IPTV, cable, satellite, DTT: what is the difference.

Proximus is the former state incumbent, Telenet the cable operator in Flanders and Brussels, VOO the cable operator in Wallonia and Brussels. The Telenet specifications come from its technical sheet for its boxes, consulted on 21 October 2026. It says what the box can display, not which channels are actually broadcast in 4K.

At Proximus, how much does one channel take? The operator publishes no figure. On its community forum, in 2020, an experienced member put it at 6.5 Mbps reserved for an HD channel on a VDSL line. Take it as an order of magnitude, not as official data. It is enough to explain many ruined evenings: two boxes switched on plus a Netflix film in 4K already make 28 Mbps.

I fitted set-top boxes for seven years around Namur, for three operators. The most frequent complaint, on Proximus copper lines, was not a fault. It was a computer that crawled as soon as the living-room TV came on. Nothing broken: the line did 30 Mbps and the TV took a good share of it.

What speed do Belgian entry-level bundles really deliver?

From 150 to 500 Mbps advertised, for €72 to €82 a month without promotion.

On 21 October 2026 I checked the cheapest internet and TV bundle with a set-top box at each operator. The last column divides the advertised speed by 25 Mbps: it is the theoretical number of 4K screens the plan supports, headroom included.

On paper, none of these plans lacks bandwidth for 4K. Even the slowest supports six screens at once.

The word that matters in this table is "up to". Proximus Flex+ Go runs over the copper VDSL line when fibre is not in the street, and on copper the speed drops with the distance to the street cabinet. I have seen the same subscription give 70 Mbps in a street in Jambes and under 25 a few kilometres away, in a hamlet near Andenne. Same price, same brochure. On the Telenet and VOO cable networks, the limit comes rather from sharing with neighbours at peak times, in the evening.

At Orange, the real entry level is even lower: Livebox with Orange TV Lite, up to 200 Mbps, €63 a month without promotion, checked the same day on Orange's bundle page. But with no box: the 20 channels run through the app.

Why does the picture break up with a plan that should be enough?

Because the contract speed almost never reaches the television intact. The causes I came across most often, in order:

• The Wi-Fi. A box or a television two rooms away from the modem easily loses three quarters of the speed. A speed test on your phone, sitting next to the modem, says nothing about what the screen receives.
• A copper line that is too long. On VDSL, beyond a few hundred metres from the street cabinet, speed tops out well below the brochure figure.
• Peak hours. Between 7 pm and 11 pm, shared networks slow down, and that is exactly film time.
• Other devices. A photo backup, an 80 GB console update or a second IPTV box take their share without warning.
• The cheap repeater. It extends coverage but often halves the speed.
• The HDMI cable or the TV setting. Rarer, but an old cable or an HDMI input set to standard mode blocks 4K even with 1 Gbps.

When the picture jumps from perfectly sharp to a mush of pixels, then recovers, the app is adapting quality to the bandwidth available. The symptom is useful: it tells you the speed fluctuates, not that it is permanently short.

Diagnosing a speed problem in five steps

Twenty minutes, an Ethernet cable and a laptop.

1. Measure over a cable. Plug the computer straight into the modem and run a speed test. That is your line's real speed, without Wi-Fi.
2. Measure where the screen is. Same test, over Wi-Fi, at the exact spot of the television or box. The gap between the two measurements is what the Wi-Fi loses.
3. Do it again at 9 pm. An afternoon measurement flatters every network. Write the results down with the date and time.
4. Cut the other uses. Switch off the second box and pause downloads, then restart the film. If 4K comes back, your line is not short of speed, it is short of room.
5. Wire the screen. If Wi-Fi is the cause, an Ethernet cable remains the most reliable fix. Failing that, powerline adapters that run over the electrical wiring, such as those sold by Devolo or TP-Link, often do better than a repeater.

If the measurement over a cable is far below the contract speed, repeatedly, the problem lies with the operator. EU Regulation 2015/2120 requires a fixed internet contract to state a minimum speed, a normally available speed and a maximum speed. A significant and recurring gap opens up remedies. Write to the operator first, with your dated measurements. If it does not answer, the Service de médiation pour les télécommunications, the Belgian telecoms ombudsman, handles the complaint free of charge, and the BIPT (IBPT in French), the federal telecoms regulator, sets out your rights.

Moving up a tier for 4K: rarely money well spent

The tier above costs €7 to €22 more a month. For 4K, it almost never changes anything.

At Proximus, going from 150 to 500 Mbps on fibre costs €7 a month more, provided fibre is in your street. At Orange, Livebox Giga with Orange TV Plus is €104 a month without promotion, €22 more than Livebox Up, checked on 21 October 2026. Over three years, the Orange gap comes to €792.

The box itself is covered in Orange TV box, which model and how to connect it and in Proximus TV box, models and how to connect them. To compare bundles on their second-year price rather than their speed, use the TV subscription ranking or the comparison tool.

Sources. Netflix, help page "Internet connection speed recommendations" (3, 5 and 15 Mbps), consulted on 21 October 2026; YouTube, "System requirements" help page (2.5, 5 and 20 Mbps), consulted on 21 October 2026; Disney+, recommended speeds (5 and 25 Mbps); Proximus, Netflix FAQ (up to 7 GB per hour in Ultra HD), consulted on 21 October 2026; Proximus community forum, threads of 30 October 2020 (6.5 Mbps reserved per HD channel on VDSL, a member's figure) and 11 April 2024 (Pickx channels in HD, 4K limited to apps); Telenet, technical sheet for its boxes, consulted on 21 October 2026; prices checked on 21 October 2026: Proximus Flex+ Go with Pickx (€75.99, 150/30 Mbps, Astel listing), Telenet Internet Basic + TV (€76, 200/20 Mbps, price checked on 19 October 2026 by providersvergelijken.be), VOO Duo Net Super Relax + TV (€72, 200/10 Mbps, Selectra, page updated on 20 October 2026), Orange internet + TV (€63, €82 and €104, orange.be); Regulation (EU) 2015/2120, Article 4.