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4K Ultrahd

Everything you need to know about 4K and UHD

The world of TVs has moved on a lot in the last few years. There are new technologies and certifications, all aimed at helping TV tech take the next leap forward. They all carry snappy acronyms like HDR and BT.2020. The one you need to look out for is ‘4K’. There has been talk of 4K for years, but it’s no longer just something for the tech-minded early adopters. This advancement has properly hit the mainstream. It is now an important new standard.

What exactly is 4K?

4K, also known as Ultra HD, generally refers to a resolution of 3,840 x 2,160 pixels. That’s four times the 1,920 x 1,080 pixels found in your full HD TV. We’re looking at about 8.3 million pixels. Cramming so many pixels into a TV means a higher pixel density, and you should have a clearer, better-defined picture. It’s not about sharpness, it’s about letting you see more detail and texture.

What is the difference between 4K and Ultra HD?

4K is by far more commonly used, but you’ll also find people calling it Ultra HD, or UHD. For the average consumer buying a TV, these are one and the same. But there is technically a difference.

In its correct usage, true 4K refers to a resolution of 4096 x 2160, which was first introduced in digital cinemas. Meanwhile, UHD refers to a resolution of 3840 x 2160, which is what you get on the TVs you actually take home.

So technically, ‘4K’ is the wrong term for 3840 x 2160 displays and content, but it’s a mistake so common that there is no functional difference anymore. For most people, the two terms are interchangeable.

What broadband speed do you need to stream 4K?

Netflix and Amazon are the big names streaming 4K, and both services need a minimum of 15Mbps to do 4K. And your speeds need to remain consistently at or above that figure. As soon as you drop lower – due to high contention rates at peak usage times, say – the picture will slip back into HD mode. And don’t worry if you start off with a blurry image: it’s quite common for streaming services to start a programme at a low resolution and then bump it up to HD and UHD after the initial buffer.

To try and cover itself for this eventuality, Netflix actually says on its website that you need 25Mbps minimum. But we’ve confirmed with Netflix that a consistent 15Mbps is enough. It’s worth bearing in mind that this means you need 15 to 25Mbps of spare bandwidth, so if someone else is using your Wi-Fi, you’ll need to have that amount of bandwidth free after you account for the other person’s usage.

Compression techniques improve all the time, so it’s possible you may in the future need slightly lower broadband speed to experience 4K on Netflix or other rival 4K streaming platforms. But bear in mind that high levels of compression inevitably negatively affect picture quality, so if you’re serious about 4K a fast broadband connection is a must.

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