How to Compress a Video on iPhone

The fastest way to compress a video on iPhone is to figure out what limit you're actually fighting, then decide whether to shrink the file or just send it a different way. Here's the full breakdown, from email limits to codec choice.

Compress a video on iPhone to get under an email limit

Gmail caps attachments at 25MB for personal accounts, replacing anything larger with a Google Drive link automatically. That limit is usually the actual constraint, so it's worth checking before deciding how much to shrink a file. A one-minute clip shot at a high resolution can sit well above 25MB even at a moderate bitrate, which is why "just attach it" so often fails on the first try.

Sending 5 GB without compressing anything

Before reaching for compression, consider not compressing at all. Mail Drop, built into Mail on iPhone, sends attachments up to 5GB, gives the recipient 30 days to download, and doesn't touch your iCloud storage. For a lot of situations, that's a faster fix than shrinking the file, and it sidesteps the actual trade-off compression always involves: smaller file, less detail.

When compression is genuinely needed, the frame size and the codec are the two honest levers. Dropping the resolution has the biggest effect, since every pixel removed is data the file no longer has to store. The codec matters too: HEVC (H.265) compresses more efficiently than H.264 at similar visual quality, which is why it's the format Apple uses by default. Settings > Camera > Formats > Most Compatible trades that efficiency for wider playback support on future recordings, and staying at 1080p or lower with 60fps or lower widens compatibility further on older hardware, but that setting only affects clips you record after changing it, not the one you're trying to send right now.

Bitrate is the third lever, and the one people reach for least even though it's often the biggest: it's the amount of data spent per second of video, and dropping it reduces the file size directly without changing the frame dimensions at all, though push it too far and the picture starts showing compression artifacts, blocky patches in fast motion or busy detail, before the file size savings become dramatic.

Exporting once, in an efficient codec

Montaj exports in HEVC (.mp4), so the file you get out is already using the more efficient codec rather than needing a separate compression pass afterward. Once you've compressed a video on iPhone the right way , codec first, frame size second, bitrate only if the first two aren't enough , sending it gets a lot easier.