Shrink a video online, free

Drop your file in below to make the video smaller. Everything happens inside this page — the video is never uploaded. Below the tool is the arithmetic for hitting a specific size limit, which is usually the reason people need to shrink a video in the first place.

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Shrinking to a size limit: the arithmetic

Most requests to shrink a video have a number attached — an attachment cap, an upload ceiling, a storage budget. File size is almost entirely bitrate × duration, so you can compute the answer instead of guessing: 

total_kbps = target_MB × 1024 × 1024 × 8 / duration_seconds / 1000
video_kbps = total_kbps × 0.96 − audio_kbps

A 6-minute clip that has to come in under 100 MB gives 100 × 1024 × 1024 × 8 / 360 / 1000 ≈ 2,330 kbps total. The 0.96 leaves room for container overhead, and 128 kbps goes to the audio, so the video stream gets 2,108 kbps — comfortable for 720p, tight but workable for 1080p on low-motion footage. That is the figure the tool solves for this clip, not an approximation of it.

Leave yourself 5–10% of headroom. Container overhead and the encoder's rate control both mean the finished file lands a little above the arithmetic, and being 2 MB over a hard limit is as bad as being 200 MB over.

Let the tool do the arithmetic

You do not have to run any of that by hand. Switch the encoder to Target size and type your ceiling in megabytes: the tool reads the clip length from the file, works the same division, subtracts an audio allowance and encodes to the bitrate that falls out. It then measures the finished file and, if the encoder overshot, scales the bitrate by exactly how far over it landed and runs again. Presets for the common ceilings open with the target already set.

The quality slider is the other route, and it answers a different question. It targets a fraction of your source bitrate — roughly 78% at the gentlest position down to about 20% at the most aggressive — so it adapts to how much slack the source actually has, but it cannot promise a number. Use the slider when you want the file smaller; use a target when something will reject it above a limit.

A 900 MB, 6-minute source is running at about 20,972 kbps. To reach the 2,108 kbps from the example above you would need about 10% of that, which is below the slider's floor — which is precisely the case target-size mode exists for, and the signal to reach for the second lever as well: resolution.

When to shrink the resolution instead

Bitrate and resolution are not independent. The same 1,500 kbps that looks poor on 1080p looks respectable on 720p, because the bits are spread across 44% as many pixels. Some rough thresholds worth knowing before you shrink a video:

  • Under 150 kbps for the video stream — no resolution rescues it; trim the clip instead.
  • 150–400 kbps — 360p.
  • 400–800 kbps — 480p.
  • 800–2,000 kbps — 720p.
  • 2,000–5,000 kbps — 1080p.
  • Above 5,000 kbps for the video stream — 1080p or original.

These are starting points, not laws: a static screen recording survives far lower bitrates than a handheld shot of moving water. Encode a 30-second sample first if the source is unusual.

Shrinking a 1080p video to 720p

Downscaling is the single most reliable way to make a video smaller, because it removes data before the encoder ever sees it. 1920×1080 is 2,073,600 pixels; 1280×720 is 921,600 — about 56% fewer. In practice the file does not shrink by exactly 56%, because a downscaled frame is also easier for the encoder to predict, so the saving is usually larger than the pixel ratio alone suggests. Pick 720p in the resolution dropdown and leave the quality slider where it is, or start from the resolution page, which opens the tool with that step already set.

What shrinking will not fix

Compression cannot recover detail that was never recorded, and re-encoding an already heavily compressed file is a losing game — you are throwing away detail from something that had little left. If a file is already small for its length and still looks bad, the source is the problem. Likewise, if you only need a different container rather than a smaller file, use Remux: it swaps the wrapper and copies the video stream unchanged, so it takes seconds and loses nothing.

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