Q. How do I take 4K videos on an iPhone?
A. Apple introduced official support for 4K video on its mobile devices in 2015 with the release of its iPhone 6s and iPhone 6s Plus models, so first make sure you are using hardware that can handle the ultra high-definition format. The 4K video option is typically off by default so once you have confirmed your iPhone model is 4K-capable, open the Settings app on the home screen.
On the main Settings screen, scroll down and select Camera. On the Camera settings screen, tap Record Video.
The next screen displays all the resolutions and frames-per-second rates you can use for recording video. Higher frame rates capture more of the motion in the scene and make the action look smoother. The 24 frames-per-second rate is fairly standard for recording on film and used by movie theaters, while the 30 f.p.s. and 60 f.p.s. rates are often used for high-definition video formats. The most recent iPhone models released last year (the iPhone 8, the iPhone 8 Plus and the iPhone X) can capture 4K video at 60 frames per second.
Because higher resolutions and frame rates mean more video data, they produce larger file sizes. The Record Video setting screen also gives you an idea of how much storage space will be taken up by one minute of video in each format.
The lowest option for 4K, 24 f.p.s., will take up an estimated 135 megabytes of space for each minute recorded, while the 30 f.p.s. setting takes up 170 megabytes of storage for every 60 seconds of captured video. On iPhones that can record 4K video at 60 f.p.s., plan to fill up about 400 megabytes of storage space for every minute of video.