File-size problems
Reduce video size without losing quality: what actually works
Short answer
You cannot shrink a video with zero loss, but you can stay visually near-lossless: trim unneeded footage, re-encode with x264 at CRF 18 to 23 and a slow preset, keep the original resolution, and use AAC at 128 to 160 kbps. The FFmpeg wiki calls 17 or 18 visually lossless or nearly so and notes that +6 CRF roughly halves the file size.
Key takeaways
- Trimming is the only reduction that costs no quality.
- CRF 17 to 18 is near lossless; 20 to 23 is a sound range for uploads.
- Slower presets save size at the same quality.
- Resolution cuts size but costs detail; use it last.
Find your case
| What you see | What it usually means | Do this |
|---|---|---|
| File is huge from a screen recorder | Very high bitrate capture | Re-encode at CRF 20 to 23 (step 2) |
| Need it under a limit but sharp | Trade-off between size and detail | Trim, then CRF 23 to 26 (steps 1 and 2) |
| Already compressed once | Further loss is more visible | Compress from the original (step 4) |
| Result is still too big | Quality target higher than the size limit allows | Raise CRF by 2 steps or cut length (steps 1 and 2) |
Fix it step by step
Trim first
Cut footage you do not need; every second removed saves bits without changing quality.
Re-encode with CRF
ffmpeg -i in.mov -c:v libx264 -crf 20 -preset slow -pix_fmt yuv420p -c:a aac -b:a 160k out.mp4.Pick a slower preset
Use the slowest preset you have the patience for; it improves compression at equal quality.
Compress from the original
Every extra generation of lossy compression adds loss. Keep the source and re-encode from it.
Order of operations
- Trim.
- Keep resolution.
- Encode with CRF and a slow preset.
- Fix audio bitrate.
- Compare at full screen, then upload.
Check your file
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Frequently asked questions
Can I reduce video size without losing quality?
Only by trimming. Re-encoding is lossy, but CRF 17 to 18 is visually near lossless according to the FFmpeg wiki.
What is the best CRF for sharp uploads?
20 to 23 is a good range; 18 for maximum quality when size allows.
Does HEVC make files smaller?
Yes, usually, but not every platform accepts it; Pinterest lists H.265, YouTube recommends H.264.
Sources
- FFmpeg Wiki: Encode/H.264 (CRF, presets) (official, checked 2026-10-06)
- YouTube Help: Recommended upload encoding settings (official, checked 2026-10-06)
- Pinterest Help: Review Pin specs (Video Pin file types and encoding) (official, checked 2026-10-06)
Reviewed 2026-10-06. Steps not attributed to a source are general video practice or computed above.