LOCAL VIDEO TOOLS · CRF AND BITRATE
Video Compressor
Pick a quality level, convert, and read the two numbers that matter: the source size and the result. Everything happens in this tab.
Choose a file. It stays on your device.
How to compress a video and read the result
- 1
Add the video. The file is read in this tab and is never uploaded.
- 2
Choose Light, Balanced or Smaller. The level sets the CRF value the encoder aims for.
- 3
Convert, then compare the two sizes shown under the preview. If the result is bigger, pick a higher level and try once more.
What the three levels change
The levels are CRF values, not size presets. CRF stands for constant rate factor: the encoder holds a constant visual quality and lets the bitrate float. A lower number means more bits for the same picture, so Light (CRF 23) keeps more detail and Balanced (CRF 28) throws some away. Smaller (CRF 34) is visibly softer on gradients, skin tones and fast motion.
As a rule of thumb, every six points of CRF roughly halves the bitrate. Two levels apart is not a fixed percentage either: the same CRF on a talking-head clip and on confetti produces very different file sizes, because the encoder only spends bits where the picture is hard.
Estimate the result before you wait for it
Size follows bitrate, and bitrate follows resolution and content. A useful estimate is megabytes = megabits per second × seconds ÷ 8. Exporting a 60-second clip at 4 Mbps gives about 30 MB, plus roughly 1 MB per minute for 128 kbps audio.
The table below is a reasonable starting point for H.264 at CRF 28. Studio footage, screen recordings of text and anything with heavy grain will land above it.
| Resolution | Video bitrate | One minute |
|---|---|---|
| 480p | 0.8–1.2 Mbps | 6–9 MB |
| 720p | 2–3 Mbps | 15–22 MB |
| 1080p | 4–6 Mbps | 30–45 MB |
| 1440p | 8–11 Mbps | 60–82 MB |
| 2160p | 16–24 Mbps | 120–180 MB |
When the file grows instead of shrinking
Compression cannot recover bits that are already gone. If the source was exported at a low bitrate, or already went through a social platform, re-encoding at CRF 28 spends more bits than the original had and the result is larger. The page tells you when this happens instead of pretending the file got smaller.
Two other cases surprise people. Very short clips are dominated by container overhead, so a three-second clip may barely move. And noise, film grain or a shaking handheld shot force the encoder to encode detail frame after frame, which is exactly where CRF spends its budget.
Resolution beats CRF when you need a target size
If you must fit a limit, halving the frame size cuts the pixel count by four and is far more predictable than nudging CRF. A 1080p clip at CRF 28 and a 720p clip at CRF 23 often land in the same range, but the 720p file looks cleaner on a phone screen while the 1080p file keeps more detail on a monitor.
The output here is always H.264 in an MP4, which is what phones, chat apps and editors accept. Keep the original until you have watched the result: a smaller file is only useful if it still looks right.
FAQ
Is CRF the same as a target file size?
No. CRF holds a quality level and lets the size fall where it falls. This tool reports the real size after the fact; it cannot promise a fixed number of megabytes.
Which level should I start with?
Balanced (CRF 28). Move to Light only if the picture looks soft, and to Smaller only if the result is still too heavy to send.
Why did a 20 MB video become 24 MB?
The source was already compressed harder than CRF 28. Re-encoding cannot restore the missing detail, and matching the quality costs more bits than the original used.
Does the audio get recompressed too?
Yes. The first audio track is re-encoded to 128 kbps AAC, so a silent screen recording and a music video behave differently in the totals.
Can I compress a video twice?
You can, but each pass loses a little detail and the second pass often saves very little. Compress once from the best source you have.
Where does the compressed file go?
Into your browser downloads, from the link under the preview. Nothing is stored on a server because nothing was sent to one.