MotionShineShort answer: 4K video is a picture that is 3840 pixels wide and 2160 pixels tall. YouTube Help lists "2160p (4K): 3840x2160", and Apple's QuickTime Player page describes its 4K export as "up to 3840 x 2160". That is four times the pixels of 1080p (1920 x 1080), so a 4K video can show more detail, and its file is bigger. It matters most on large screens and when you plan to zoom in on part of the picture.
Checked on 23 October 2026. Sources: YouTube Help "Recommended upload encoding settings" and "Choose the right resolution", and Apple Support "Export movies to other file formats and resolutions using QuickTime Player on Mac". The pixel maths below is my own sum.
4K compared with other sizes
| Name | Pixels (wide x tall) | Total pixels | Compared with 1080p |
|---|---|---|---|
| 4K (2160p) | 3840 x 2160 | 8,294,400 | 4 times |
| 1080p | 1920 x 1080 | 2,073,600 | 1 time |
| 720p | 1280 x 720 | 921,600 | 0.44 times |
The totals are width times height. 8,294,400 divided by 2,073,600 is exactly 4.
Does 4K mean better quality?
Not by itself. More pixels can hold more detail, but the picture is only as good as what was recorded and how it was compressed. A 4K file squeezed too hard can look worse than a 1080p file with enough data. The amount of data per second is the bitrate. What is video bitrate? explains it.
What 4K does to file size
YouTube's recommended upload bitrates for standard frame rates are 35 to 45 Mbps for 2160p and 8 Mbps for 1080p. That is roughly 4 to 6 times more data every second. These are YouTube's upload recommendations, not what a Mac recorder produces. Your own file depends on the app, the codec and what is on screen. To see what a given length costs, use the free bitrate and file size calculator.
When to record your screen in 4K
Record in 4K when:
- You will zoom in. Zooming enlarges part of the frame. A 4K source leaves more detail in the zoomed area than a 1080p source does.
- Viewers use big screens. On a large monitor or TV, small text stays crisp.
- You want to keep a master. You can export a smaller version for each place you share it.
- The screen is high resolution. Tiny interface text shows best at full size.
Stay with 1080p or lower when:
- The file must be small. Email and chat apps have size limits.
- Viewers watch on phones. A small screen shows little extra detail.
- The recording is long. Hours of 4K fill a disk quickly.
This is advice from how pixels work, not a test I ran.
Where MotionShine fits
MotionShine is a free Mac screen recorder, made by the writer of this blog. Free exports go up to 720p at 30 fps with no watermark and no time limit. Pro unlocks 1080p, 1440p and 4K, plus 60 fps. It is not for you if 720p is enough, because then the free version covers everything.
How to make a 4K video smaller
Export a lower size, or compress it. How to compress a video on Mac shows five ways. The free video compressor runs in your browser. If you are choosing a codec, see H.264 vs HEVC for screen recordings.
FAQ
What is 4K resolution?
3840 x 2160 pixels, according to YouTube Help and Apple's QuickTime page. It is also called 2160p or Ultra HD.
Is 4K the same as 2160p?
For video, yes. 2160p means 2160 pixels tall, and YouTube Help pairs 2160p with 4K at 3840x2160.
Is 4K four times better than 1080p?
It has four times the pixels, but quality depends on the recording and compression too. It is not four times better to the eye.
Does QuickTime Player export 4K?
Yes. Apple's page lists 4K as an export choice, up to 3840 x 2160. Sizes larger than your movie are dimmed in the menu.
Can MotionShine export 4K for free?
No. Free exports go up to 720p at 30 fps. Pro unlocks 4K.
How big is a 4K video file?
It depends on the bitrate and length. Size equals bitrate times seconds, divided by 8 for megabytes. The calculator does the sum for you.
