Starting from iPhone X, users could record videos at 4k@60fps, which take significant amount of internal storage. A 10-minute 4k@60fps video may consume 4GB of space, which is unacceptable if you have a basic iPhone variant with only 64GB storage. If you want to keep high quality videos in your iPhone, you can optimize it to reduce file size.
Resize
Sometimes, you don’t really need 4k videos, because they look just fine in 720p or 1080p resolution. There are multiple apps on the App Store that help to reduce video resolution. If you want to share the video to social media, you may reduce the resolution to 480p or 720p. Resizing your videos with these apps is fairly similar. Choose a video and specify the resolution and frame rates. Choose smaller numbers to get a file with smaller size. Tap the Resize button in the app and wait until it’s completed.
Compress
 If you insist on using the same resolution, your next option is to use a compression app. With Video Compress and similar video compression apps on the App Store, you can make videos smaller in size, without causing discernible reduction in quality. These apps are fairly easy to use and it’s not necessary to configure advanced options. Download and open the compression app and choose the file format for the output file, if you want to export the file. Choose the video file and set the preferred compression ratio. If you choose an aggressive compression, the overall video quality could be less than desirable. It takes some tries to get maximum file size reduction with acceptable video quality. Tap the compress button and wait until the completion of the process.
Online compression
Using online compression is more convenient, because you don’t need to install and configure anything. Clideo and other online compression websites allow you to quickly upload a video and compress it. If you have a high-speed Wi-Fi connection, it is method to choose. A 5-minute 4k video could take up around 2GB of space, so be sure that your connection is sufficiently fast. If you don’t have time to wait, you can do it overnight while you’re sleeping. Remember that these free services may add watermark to compressed videos, which is not a problem for personal users. On your iPhone, open Safari web browser and go to Clideo or a similar site. Choose a video file, file type and compression ratio. It will take time to upload and compress the video file. The website will give you a link to download the compressed video file.
Convert
iPhone uses H.264 QuickTime in MOV format when recording videos to ensure the highest quality, regardless of the file size. Your 4k and 1080p videos look great, but they eat up a lot of space. MKV or MP4 format with x265 video codec and AAC audio codec offers acceptable quality at relatively minimum file size. Media Converter is a popular free video converter app on the App Store, but you can choose any other app. Download the video converter app, choose a video file, choose MKV or MP4 format, select quality settings and tap the convert button.
Record With Smaller Resolution
After optimizing your 4k and 1080p videos, you should consider choosing 720p resolution when recording with your iPhone. This resolution still looks quite acceptable on your iPhone and social media. With iOS 14, go to the Camera settings and enable the Video Format Control toggle. Choose 720p@30fps resolution for ideal quality and file size. When recording a video, check the top right corner of the display. It should show the resolution and frame rate of the recorded video.
