How to turn an iPhone MOV into a smaller MP4

You record a video on an iPhone, try to upload it, and the site complains about the format or the size. iPhone videos are large and use a format that not every website or older device understands. Here is how to fix both problems at once.

In short

Why iPhone videos cause trouble

By default, recent iPhones record in a high efficiency format: HEVC (also called H.265) video, usually saved in a MOV file. HEVC makes small files at good quality, but it needs a compatible decoder, and many websites, older computers and some messaging tools cannot play or accept it. The videos are also big, because phone cameras record at high resolutions and frame rates.

Step by step

  • Open the video compressor and drop in the .mov file. On a phone, choose it from your library.
  • Pick the size you need. Phone videos often need a big reduction, so check the quality indicator before you start.
  • If the video is long, trim it to the part you need first.
  • Compress and download the MP4. It uses H.264 video and AAC audio, which plays almost everywhere.

A real example

A 20-second 1080p60 screen recording, aimed at a 10 MB limit:

1080p60 → 720p60Audio copied untouchedAbout 6 seconds in Chrome on a Mac
The compressor planned the resolution from the size budget, kept the original audio, then measured the real file: 9.7 MB, under the 10 MB limit.
Technical details

Codec, container and what changes

A video file has two layers. The container (MOV or MP4) is the box that holds the streams, and the codec (HEVC or H.264) is how the picture is compressed. MOV and MP4 are very similar boxes. The compatibility problem is almost always the codec.

The compressor decodes your HEVC video with your browser’s decoder and encodes it again as H.264 inside an MP4. If your browser or computer cannot decode HEVC, it falls back to a WebAssembly engine that can, which is slower. Re-encoding always loses a little detail, so start from the original recording and avoid converting twice.

Avoid the problem at the source

On recent versions of iOS you can ask the iPhone to record in a more compatible format: open Settings, then Camera, then Formats, and choose Most Compatible. Videos then use H.264 and are saved as MP4-compatible files. They are bigger than HEVC videos, so you will still want to compress them before sharing.

Will the quality drop?

A little, and how much depends on how small the target is. A phone video of a minute can be several hundred megabytes. Fitting it into a chat or email limit means a lot of reduction, so the compressor lowers the resolution first if it must. Trim the video and lower the target step by step until the preview and the estimate look acceptable.