Compression · Knowledge
How Bitrate Affects File Size
For audio you will see kbps; for video, effective bitrate or quality/CRF-style proxies. Duration × bitrate dominates file size for media streams.
Quick take: Halving bitrate roughly halves media stream size for the same duration — with a quality cost. Prefer lowering resolution or duration before crushing bitrate too far.
Audio
A 3-minute track at 320 kbps is far larger than the same track at 96 kbps. Speech tolerates lower rates; music shows muffling sooner.
Video
Bitrate shares the budget across frames. Busy motion and high resolution need more bits. Quality sliders in browser compressors map to how aggressively the encoder spends that budget.
Practical guidance
Use Format Convertly’s video and audio compressors, preview when you can, and keep masters. If the file is still huge, shorten the clip or lower resolution before annihilating bitrate.
Key points
- Size ≈ bitrate × duration (for the media stream).
- Lower bitrate shrinks files and can hurt quality.
- Resolution and length matter as much as the slider.
Open a compressor
Shrink files privately in your browser — pick a category, then a format tool when you know the extension.
Re-encode common video containers to a smaller MP4 in your browser.
Re-encode audio to a smaller MP3 — podcasts, voice notes, and music shares.
Related compression guides
Related quality guides
Related concepts
FAQ
Is CRF the same as bitrate?
Not exactly. CRF-style quality modes let size vary to hit a quality target; bitrate modes target a size budget. Both affect how much detail survives.
Why didn’t my file shrink much?
The source may already be low bitrate, or the setting stayed high. Try a lower quality/bitrate bias, or confirm you re-encoded instead of remuxing.
Browse all compression guides, compressors, or quality guides.