MOV is Apple's native video container format. When you record video on a modern iPhone or Mac, the file is saved as a .mov file, typically encoded with HEVC (H.265). This works perfectly within the Apple ecosystem. The problems start when you try to share that file outside of it.
Why MOV files cause problems
The issue is not the MOV container itself, which is well-supported on most modern devices. The real problem is usually the codec inside the container. Modern iPhones record using HEVC (H.265) by default because it produces smaller file sizes than H.264. However, many Windows PCs, older Android phones, and web browsers cannot decode HEVC natively without paying for a codec license or installing additional software.
When someone on Windows receives a .mov file from an iPhone user and it "will not play," the cause is almost always that the HEVC codec is missing. Windows 10 and 11 require a paid HEVC Video Extensions package from the Microsoft Store (or the free "HEVC Video Extensions from Device Manufacturer" if available on the device).
Why MP4 is the universal format
MP4 is the most widely supported video container format in existence. When encoded with H.264 (the older but universally compatible codec), an MP4 file will play on essentially every device manufactured in the last 15 years: Windows, macOS, Linux, Android, iOS, every web browser, and every smart TV.
Converting your MOV to MP4 with H.264 encoding solves the compatibility problem completely. The recipient does not need to install anything.
Does converting reduce quality?
Yes, slightly. Converting from HEVC to H.264 requires re-encoding the video, which is a lossy process. However, at the default settings most tools use (CRF 23 for standard quality), the visual difference is minimal and undetectable to most viewers. The trade-off is universal compatibility versus a marginal quality reduction.
If you want to minimize quality loss, the ideal CRF for H.264 is 18-20. This produces a larger file but preserves nearly all visual detail. For sharing via messaging apps or social media, CRF 23-28 is more practical because the file size is significantly smaller.
How to convert MOV to MP4 in your browser
The MediaBrew format converter handles this conversion directly in your browser. Upload your MOV file, select MP4 as the output format, and download the converted file. The tool uses FFmpeg compiled to WebAssembly, so the conversion happens entirely on your device. No file is uploaded to any server, and the process works offline once the page has loaded.
The tool automatically applies web-friendly settings: H.264 video codec, AAC audio, and the faststart flag for instant web playback. The output plays on every device and platform without codec issues.