Out of the box, your iPhone will not record 4K video. If you want to boost your video quality beyond 720p or 1080p HD, you'll need to do it manually. However, not all iPhone models can actually shoot in 4K resolution. If you have an iPhone 6 or lower, you're out of luck, but if it's the iPhone 6S or later, you can not make the 4K a problem.
To be extra clear, the only iPhone models to get 4K video recording include the following. If you have one of these devices, read on to learn all about recording video in 4K resolution with the Camera app.
- iPhone 6S
- iPhone 6S Plus
- iPhone 7
- iPhone 7 Plus
- iPhone 8
- iPhone 8 Plus
- iPhone X
- iPhone SE
How to activate 4K -Videos
Open the settings under "Camera" and then tap "Record video". Next, select the quality you want to record. There are four or six different options, one or three of which are for 4K resolution. The higher the frame rate, the softer the image and the larger the video file (more on this below).
- 720p HD at 30 fps
- 1080p HD at 60 fps  4K at 24 fps *
- 4K at 30 fps
- 4K at 60 fps *
* These options are only available for the iPhone 8, 8 Plus and X models.
The page above gives you a handy breakdown of how much memory each capture quality requires for a one-minute video. Spoiler Warning: It takes a lot of disk space. If you have a 16GB iPhone, you may want to avoid 4K video, as it would only take about 40 minutes to fill 4K 60 fps on your entire hard drive.
According to Apple, a minute video is about:
- 40 MB with 720p HD at 30 fps (space saver)
- 60 MB with 1080p HD at 30 fps (default)
- 90 MB with 1080p HD at 60 fps (softer)
- 135 MB with 4K at 24 fps (film format)
- 170 MB with 4K at 30 fps (higher resolution)
- 400 MB with 4K at 60 fps (higher resolution, smoother)
Within the video camera interface, you can see in the Camera app the quality you are shooting right next to the shutter button. However, if you use the default setting of 1080p at 30 fps, this indicator does not exist.
What's the difference?  To keep it simple, 4K means more pixels ( 4096 x 2160); about 8 million pixels more than 1080p (1920×1080). To help you you can see the difference, here's a comparison of the standard quality versus 4K (note that you need a display capable of seeing 4K videos to really see the difference and pay attention to select "4K" from the Quality menu.
1080p @ 30 fps:
So you're planning on switching to 4K recording on your new iPhone, or 1080p is fine for you Sound out in comment section below.