PDF, video and audio size targets
Download a source or run it here using the same compressor as the homepage. The table reports the bytes from your run; no output size is assumed in advance. One KB here means 1,024 bytes.
| File | Input bytes | Target bytes | Output bytes |
|---|---|---|---|
| VIDEO output | 2,334,407 | 204,800 | 183,848 |
Reference method: the PDF uses the actual PDF processor with a Node canvas adapter; video and audio use native FFmpeg with the same encoding arguments and bitrate search as the browser processor. Browser encoders can return different sizes. See method and measurements.
Three-second video → 200 KB
A silent 1280 × 720 moving test chart. The actual browser encoder aims below 204,800 bytes. Play the output and inspect moving edges; duration and dimensions should remain unchanged.
A target that should be rejected
For this three-second video, a 1 KB target is below the processor's minimum. The expected result is an explanation asking for a larger limit, with no pretend successful output.
Video and audio processing loads the browser encoder on the first run. Keep this page open. A small target can reduce quality, still produce an oversized file, or be rejected; a completed run does not guarantee that the result suits your destination.
Video files become large quickly because they store many images every second plus audio. A ten-second clip recorded at a high resolution can be larger than a long document. To make a video genuinely smaller, you usually need to change one or more of five variables: duration, resolution, frame rate, video bitrate, and codec.
The goal is not simply to choose the lowest quality setting. It is to spend the available file size on the information viewers will actually notice. A talking-head video for email needs different settings from a fast sports clip or a product demo containing small text.
The simple relationship behind video file size
Approximate file size is controlled by total bitrate multiplied by duration. A useful estimate is: file size in megabytes ≈ total bitrate in megabits per second × seconds ÷ 8. The total bitrate includes both video and audio. Container overhead makes the final number slightly different, but the estimate is good enough for planning.
How to reduce a video for a specific limit
- Find the real destination limitEmail providers, application forms, and social networks apply different limits. Confirm whether the limit covers one file or the full message or post.
- Trim firstRemove silence, failed takes, static openings, and content after the useful ending. Shortening a video reduces size without lowering the quality of the remaining frames.
- Open Fitabyte CompressChoose video in Compress, select your source file, and enter the desired byte target. The tool does not expose a manual quality slider for video.
- Choose sensible dimensionsFitabyte retains the source frame dimensions and does not provide resolution, frame-rate or trimming controls. Make those edits in a video editor before selecting the source if required.
- Process and previewWatch sections with motion, faces, gradients, and text. These reveal blockiness, smearing, banding, and unreadable detail faster than a static first frame.
- Verify the whole resultCheck file size, duration, audio synchronization, orientation, and playback before deleting or archiving anything.
Which setting should you change first?
| Control | File-size effect | Quality trade-off | Best use |
|---|---|---|---|
| Trim duration | Direct and predictable | No loss in kept sections | Remove unnecessary footage first |
| Lower bitrate | Large | More artifacts in motion/detail | Fine-tune toward a size target |
| Lower resolution | Large | Less fine detail | 4K or 1080p is unnecessary for the destination |
| Lower frame rate | Moderate | Motion becomes less smooth | Talking heads, slides, or static scenes |
| Lower audio bitrate | Small to moderate | Audio can sound thin | Speech clips; avoid overdoing it for music |
| Use efficient codec | Potentially large | Compatibility can change | Destination supports the selected codec |
Resolution
Resolution describes the frame dimensions, such as 3840 × 2160 for 4K, 1920 × 1080 for 1080p, or 1280 × 720 for 720p. Reducing 4K to 1080p removes three quarters of the pixels per frame. That can dramatically reduce the bitrate needed for a clean result. Do not reduce resolution until interface labels, subtitles, product details, or document text become hard to read.
Frame rate
A 60 fps video contains twice as many frames as a 30 fps video of the same duration. Fast motion benefits from more frames; a person speaking to camera, a slide presentation, or a simple screen recording often works well at 30 fps. Converting 30 fps to 24 fps produces a smaller difference and may create uneven motion if handled poorly.
Bitrate and codec
Bitrate controls how much data the encoder spends per second. Too little produces blocks, smearing, and muddy textures. A more efficient codec can achieve comparable quality with less data, but not every device or platform supports every option. MP4 with H.264 remains broadly compatible. Newer codecs can be more efficient, but compatibility should be tested before sending an important file.
Adjust compression to the content
- Talking head: protect facial detail and clear audio; 720p or 1080p at 30 fps is often sufficient.
- Screen recording: keep text readable; resolution may matter more than a high frame rate.
- Sports or gaming: motion needs more bitrate and may benefit from 60 fps.
- Product demo: preserve labels, texture, and color; crop unused background before lowering quality.
- Music performance: do not reduce audio bitrate too aggressively even if the image is simple.
- Security or evidence clip: keep an untouched original and avoid edits that remove relevant detail.
Common problems after compression
- Blocky movement: bitrate is too low for the amount of motion or detail.
- Blurry text: resolution is too low or the source was already compressed.
- Color bands in skies or walls: gradients received too little data.
- Audio out of sync: verify the downloaded result from beginning to end.
- Video will not play: the receiving device may not support the codec even if it recognizes the file extension.
- Correct size but poor quality: trim more footage or use a link instead of forcing an unrealistic target.
When a hard email limit would make the video unwatchable, share a cloud link with appropriate permissions. If the file is a still image or PDF instead, use the dedicated guides for exact-size image compression and smaller PDFs.