Streaming Technology
HDR Formats Explained: HDR10, HDR10+, Dolby Vision and HLG
What HDR is, how HDR10, HDR10+, Dolby Vision and HLG differ, what you need to watch HDR when streaming, and how to fix HDR that looks too dark or washed out.
Resolution labels are everywhere — on TVs, streaming plans and app settings — but the numbers do not tell the whole story. A 4K stream can look worse than a good Full HD one, and on a small screen at a normal distance you may not see the difference at all. This guide explains what the resolutions mean and what actually determines picture quality.
The resolutions
| Name | Pixels | Also called |
|---|---|---|
| SD (standard definition) | Around 720 × 576 or 640 × 480 | 480p / 576p |
| HD | 1280 × 720 | 720p, “HD Ready” |
| Full HD | 1920 × 1080 | 1080p, FHD |
| 4K Ultra HD | 3840 × 2160 | 2160p, UHD |
| 8K | 7680 × 4320 | 4320p |
Full HD has about 2.25 times the pixels of HD, and 4K has four times the pixels of Full HD.
Resolution is not the same as quality
Three factors matter as much as resolution:
Bitrate
Bitrate is how much data per second the stream uses. Video is compressed, and a higher bitrate leaves more detail intact. A 4K stream squeezed into too low a bitrate shows blockiness and smeared detail that can look worse than a well-encoded 1080p stream.
Codec
Newer codecs such as HEVC and AV1 compress more efficiently than the older H.264, so they deliver similar quality at lower bitrates. Video codecs explained covers the details.
Dynamic range
HDR (high dynamic range) affects brightness and colour rather than sharpness, and on a capable TV it can be a more visible improvement than the jump from Full HD to 4K. See HDR formats explained.
Will you see the difference?
Whether you notice more resolution depends on screen size and how far away you sit. The closer you sit and the larger the screen, the more detail you can resolve.
- On a phone, the difference between 1080p and 4K is very hard to see.
- On a 40–43 inch TV viewed from across a living room, 1080p and 4K can look similar, especially with fast-moving content.
- On a 55 inch or larger TV at a typical distance, a good 4K stream is usually noticeably sharper.
Your TV also upscales lower-resolution video to fill its screen. Modern TVs do this well, which narrows the gap further.
What you need for 4K streaming
- A 4K TV (or 4K monitor).
- A 4K-capable device — the TV’s own apps or a 4K streaming stick or box.
- An HDMI connection that supports 4K, typically HDMI 2.0 or newer with HDCP 2.2, and a suitable cable.
- A service and plan that offer 4K for the content you want.
- Enough stable bandwidth. Services typically recommend somewhere around 15–25 Mbps for 4K; check your service’s own guidance. See internet speed for streaming.
If any link is missing, you will get a lower resolution.
How to check what you are actually getting
- Many TVs show the incoming resolution when you press the info button.
- Some streaming apps include a playback information or “stats” overlay.
- Streaming devices show the output resolution in their display settings — but the output resolution is not the same as the content resolution. A device outputting 4K may be upscaling a 1080p stream.
Is 4K worth it?
If you have a large TV, sit relatively close, and have a stable connection, 4K is usually worth having for films and nature documentaries. For news, older series and a lot of live content — often produced at 1080p or lower — it makes little or no difference. HDR, a good bitrate and a stable connection often contribute more to how a picture looks.
Why your 4K stream sometimes looks soft
Adaptive streaming lowers quality when the connection struggles, so a 4K stream may drop to 1080p or lower for a while. Why streaming quality drops explains this behaviour.
Common questions
Does a 4K TV make HD streams look worse?
A 4K TV upscales lower-resolution video to fill its screen. Modern TVs upscale well, so HD content generally looks fine, though it will not be as detailed as native 4K. Poor-quality sources can look softer on a large 4K screen.
Is 4K worth it on a phone or tablet?
Rarely. On small screens, the difference between 1080p and 4K is very hard to see, and 4K uses much more data. Lower resolutions are usually the better choice on mobile.
What is the difference between 4K and UHD?
In streaming and TVs, the terms are used interchangeably for 3840 × 2160. Strictly, the cinema “4K” standard is slightly wider, but that distinction rarely matters for home viewing.
Summary
Resolution is only one part of picture quality. Bitrate, codec and HDR matter just as much, and screen size and viewing distance decide whether extra pixels are visible. For most homes, a well-encoded stream on a stable connection beats chasing the highest number on the label.