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 |
|---|---|---|---|
| AUDIO output | 288,078 | 24,576 | 23,921 |
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 test tone → 24 KB
A synthetic 440 Hz test tone, not speech or music. The WAV is encoded to AAC in an M4A file. Start playback at low volume and check the full three-second duration.
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.
For compressed audio, file size is closely tied to bitrate and duration. A 128 kb/s stream uses about 0.96 MB per minute: 128 kilobits × 60 seconds ÷ 8 ≈ 960 kilobytes, before small container differences.
Approximate audio sizes per minute
| Bitrate | Approx. MB/min | Typical implication |
|---|---|---|
| 64 kb/s | 0.48 MB | Compact speech; limited music fidelity |
| 96 kb/s | 0.72 MB | Good speech and lightweight mixed audio |
| 128 kb/s | 0.96 MB | Common general-purpose compressed audio |
| 192 kb/s | 1.44 MB | More headroom for music |
| 256 kb/s | 1.92 MB | Higher-quality compressed listening |
These are estimates. Codec, channel count, variable bitrate, metadata, and container overhead can shift the final result.
Speech and music have different needs
- Voice notes can remain intelligible at much lower bitrates than dense music.
- Stereo music needs more information than a mono spoken recording.
- Background noise consumes bitrate without adding useful speech detail.
- A clean source compresses better than a clipped or distorted recording.
- If the audio will be edited later, preserve a high-quality master and compress only a delivery copy.
Choose a target from the duration
A 30-minute recording targeted to 10 MB has only about 44 kb/s total available. That may be workable for speech but not for music. The same 10 MB target for a three-minute clip leaves roughly ten times more bitrate per second.
Fitabyte’s browser media compressor derives an audio bitrate from the target and duration and exports a compact playable copy. If the requested target is too small for the duration, the tool stops instead of pretending a reasonable result is possible.