Video Size Reducer

File size is bitrate times duration

A video file's size is essentially its bitrate multiplied by how long it runs. Ten minutes at 8 Mbps lands around 600 MB whether it came off a flagship phone or a decade-old camera. Resolution, frame rate, and codec all matter, but they matter because of how they push the bitrate around — not on their own.

That is why "just make it 720p" is unreliable advice. Dropping the resolution lowers the bitrate an encoder needs, but if the original was already conservatively encoded you throw away visible detail for a file that barely shrinks. Working from a target size instead is the same equation solved backwards, and it keeps your original resolution intact for as long as the target allows.

Four things decide how far your file compresses

Duration

The only strictly linear factor. Halve the running time and you halve the size at the same bitrate. If a clip only needs to show thirty seconds of a five-minute recording, trimming beats compressing.

Resolution and frame rate

Going from 4K to 1080p removes three quarters of the pixels, and 60 fps to 30 fps halves the frames. Both cut the bitrate an encoder needs, but both are visible changes — reach for them after bitrate, not before.

Motion and detail

The factor most people underestimate, and usually the largest. Video codecs store the differences between frames, so footage where little changes compresses enormously. A screen recording of a mostly static document can drop by 95%. Handheld footage of moving water, foliage, or a crowd changes nearly every pixel every frame and may only give up 20–30% before artefacts show.

How it was encoded the first time

A camera original or screen-capture file usually carries far more bitrate than it needs, so there is a lot of slack to remove. A clip already exported for social media has had that slack squeezed out once — compressing it again costs visible quality for a much smaller saving.

Lower the bitrate before you lower the resolution

Most oversized files are oversized because of generous bitrate, not because of resolution. A phone recording 1080p at 20 Mbps is spending roughly four times what the same footage needs. Trimming that back is largely invisible — you are removing headroom the picture was not using. Only once the bitrate is genuinely tight does reducing resolution become the better trade, because at that point the encoder has too few bits for the pixels it is being asked to draw, and you would rather have a clean 720p picture than a blocky 1080p one.

This is what Recommended compression does by default: it holds your source resolution and works on the bitrate. Setting a target size or a lower output resolution is there for when you have a hard ceiling to clear and need the tool to make that trade for you.

H.264 or H.265?

H.265 (HEVC) reaches roughly the same perceived quality as H.264 at noticeably lower bitrate, which makes it the better choice when the target size is the binding constraint. The costs are that it encodes more slowly and that playback support, while broad, is not universal — some older devices, browsers, and chat clients will refuse the file or fall back to a download instead of an inline preview.

The practical rule: choose H.264 when the file is going somewhere you do not control — a Discord channel, an email attachment, a client's laptop — because compatibility matters more than the last few megabytes. Choose H.265 for archive copies, personal storage, and anywhere you know what will play it.

Do not forget the audio track

Audio is a small share of a long, high-bitrate video and a surprisingly large one of a short, heavily compressed clip. A stereo track at 256 kbps costs about 1.9 MB per minute — on a two-minute clip squeezed toward a 10 MB target, that is close to 40% of your budget spent before a single frame is encoded.

Completed tasks deliver AAC audio when the source has an audio track, which is both efficient and universally playable. If a recording is silent, or the sound genuinely does not matter for what you are sending, removing the track outright frees that entire budget for the picture.

Common targets, and what they hold

Rough guidance for 1080p H.264 footage of ordinary complexity. Static or screen-recorded content will fit considerably more; high-motion footage less.

What compression cannot do

It cannot recover detail that was never captured, and it cannot un-compress a file that has already been squeezed. Running an Instagram export through a compressor a second time mostly costs you quality. It also cannot make an arbitrarily long video arbitrarily small — past a certain point the only honest options are trimming the footage, dropping the resolution, or accepting visible artefacts.

There is a practical ceiling on the way in, too: visitor and free-account source files are capped at 1 GiB, and subscriber uploads at 10 GiB. For anything larger, trim the source first or export a lower-resolution master from your editor before compressing.