How to reduce video file size without ruining it
The three levers that actually control file size, and which one to reach for first.
Size is bitrate × time
Everything else is detail. A file is big because it carries a lot of data per second, or because it runs for a long time. That gives you your first and best lever: if you only need part of the video, cut it before you compress it. Halving the duration halves the size with no quality cost whatsoever, which no amount of clever encoding can match.
Then reduce the resolution
1080p carries more than twice the pixels of 720p. If the video will be watched on a phone, in a chat app, or in a small embed, 720p is genuinely indistinguishable and roughly half the size. Going to 1080p at a starved bitrate is the worst of both worlds — you keep the pixel count and lose the detail that justified it.
Only then touch the bitrate
Once the duration and resolution are right, the bitrate is what fits the file to a target. Working backwards from a size — 25 MB for email, 16 MB for WhatsApp — is easier than guessing at a quality slider, which is exactly how our compressor is built.