Video compressor

How to use the video compressor

1. 01Choose your video file, or drop it onto the box.
2. 02Pick Smallest file, Balanced or Higher quality, or enter a target size in MB.
3. 03Optionally cap the resolution to 1080p, 720p or 480p.
4. 04Click Compress video, then download the compressed video.

How much can a video be compressed?

A compressed video is smaller because it is given less data to describe the same picture with, and that trade-off comes from two independent levers: how many bits each pixel gets to work with, and how many pixels there are in the first place. Neither lever has a single right setting; the sensible choice depends on what the file needs to look acceptable for and where it is going next.

This tool's three quality presets set how many bits per pixel the encoder is given, at an assumed 30 frames per second: Smallest file uses the least, Balanced sits in the middle, and Higher quality uses the most, so the same footage produces a smaller, softer result at Smallest file and a larger, cleaner one at Higher quality. There is no number that tells you in advance exactly how much smaller a given clip will end up: it depends on the source's resolution and on how much motion and detail the footage actually contains.

Cutting the resolution is the other lever, and it works alongside the quality preset rather than instead of it: fewer pixels means less for the same bits-per-pixel setting to describe, which is often the more visually forgiving way to shrink a file that is being viewed at a smaller size anyway, such as a phone screen or a chat attachment.

Compressing to fit an upload limit

Switch to a target size by entering a number in the Target size field, and the tool works out the video bitrate that fits your clip's duration into that size, using the same arithmetic as our video file size calculator: the total bitrate a size and duration allow, with the audio share subtracted first. Audio is fixed at 96 kbps in target size mode here, rather than a figure you set yourself.

The bitrate that comes out of that sum is never allowed to go higher than whatever the chosen quality preset would already use: if a generous target size would technically allow a higher bitrate than Smallest file, Balanced or Higher quality calls for, the tool uses the lower, preset figure instead. Picking a quality first and a target size second gives the more predictable result.

If the target is too small for the clip's length, even at zero video bitrate the audio alone would not fit, and the tool says so rather than producing a file that silently overshoots the limit; shortening the clip or raising the target size are the two ways to fix that.

Lowering the resolution

The resolution options cap the shorter side of the frame, not a fixed dimension: for ordinary landscape footage the shorter side is the height, so picking 720p caps the video at 720 pixels tall and scales the width to match. For a portrait or vertical video, the shorter side is the width instead, so the same 720p option caps the width at 720 pixels rather than the height.

Capping resolution never scales a video up: choosing 1080p on a source that is already 720p leaves it at 720p rather than stretching it larger, since upscaling adds no real detail and only makes the file bigger for no visual benefit. The cap only does something when the source is larger than the option chosen.

Because the resolution cap and the quality preset act independently, a heavily compressed file at full resolution and a lightly compressed file at a capped resolution can end up close in size while looking quite different: soft detail across the whole frame in the first case, a smaller but cleaner picture in the second.

How the numbers are worked out

Quality presets turn the frame size into a bitrate: bitrate = width x height x 30 x bits-per-pixel, using an assumed 30 frames per second and 0.05 for Smallest file, 0.08 for Balanced, or 0.12 for Higher quality.

That preset bitrate is then capped at 90% of the source's own average video bitrate, estimated from the file's size and length minus an assumed 96 kbps of audio, and never set below 150 kbps, so an already efficient file is not re-encoded at a higher bitrate than it had.

Target size mode uses the video file size calculator's own formula in reverse, solving for the video bitrate a given size and duration allow with audio fixed at 96 kbps, then caps that figure at whatever the chosen quality preset would already use, so it is never pushed higher.

Questions about the video compressor

How do I compress a video without losing quality?

Strictly, you cannot: re-encoding is a lossy step, so every setting here changes the picture in some way. Higher quality keeps the most detail of the three presets, at the largest resulting file size for the same footage, and is the setting to pick when quality matters more than size.

Can I compress a video to a specific size?

Yes. Enter a number in the Target size field and the tool solves for the video bitrate that fits your clip into that size, using the same sum as our video file size calculator with audio fixed at 96 kbps. The bitrate never goes above whatever the chosen quality preset would already use.

Why is the compressed file bigger than expected?

The browser's encoder varies bitrate around a target average rather than holding it exactly, and the output container adds a small amount of its own structural overhead on top of the compressed video and audio; both of those can push a finished file a little past a quick multiplication of the numbers above.

Is my video uploaded?

No. The whole compression runs in your browser; your video, and the compressed file it becomes, never leave your device.

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Updated 22 September 2026 · All free tools