What the High, Medium and Small quality settings actually do
2026-10-01
Every converter on this site has a three-way quality switch. It is not a vague slider: each option maps to fixed encoder settings, listed below. Knowing them makes it easier to choose, and to predict how large the result will be.
Video (MP4, MOV, MKV)
Video is encoded with x264 (H.264) using a constant rate factor (CRF). CRF tells the encoder how much detail it may discard: lower numbers keep more detail and produce larger files. Audio inside the video is encoded as AAC.
| Setting | Video (x264 CRF) | Audio (AAC) | Use it for |
|---|
| High | CRF 20 | 256 kbps | A copy you will edit again or keep as your master |
| Medium | CRF 24 | 192 kbps | Sharing, uploading, everyday playback |
| Small | CRF 28 | 128 kbps | Messaging apps and email attachments |
One thing to know: the encoder runs with the ultrafast preset, because a browser has far less processing power available than a desktop encoder. Ultrafast is quick but compresses less efficiently, so at the same CRF the file is larger than what a slow desktop encode would produce. If the result is bigger than you expected, drop one step rather than assuming something went wrong.
WEBM uses the VP8 encoder with a target bitrate instead of CRF: 2 Mbps, 1 Mbps and 500 kbps for High, Medium and Small.
Audio
| Target | High | Medium | Small |
|---|
| MP3, M4A, AAC | 256 kbps | 192 kbps | 128 kbps |
| OPUS | 160 kbps | 128 kbps | 64 kbps |
| OGG (Vorbis) | quality 7 | quality 5 | quality 3 |
| WAV, AIFF, FLAC | Lossless: the setting has no effect | | |
For music, Medium (192 kbps MP3) is where most listeners stop hearing a difference. For speech, such as lectures and voice memos, Small is fine and OPUS at 64 kbps is the most efficient choice.
Images
JPG and WEBP use the browser's own encoder at quality 95, 85 and 70 (out of 100). PNG, BMP and TIFF are lossless, so the switch does nothing for them. The image keeps its original pixel dimensions; the one exception is ICO, which is resized to fit within 256 × 256.
GIF from video
| Setting | Frame rate | Width |
|---|
| High | 15 fps | 640 px |
| Medium | 12 fps | 480 px |
| Small | 8 fps | 320 px |
GIF is the one target where the setting changes size and smoothness, not just compression. See making a GIF from a video for how to keep the file manageable.
Which one should you pick?
- Not sure: leave it on Medium.
- You will edit the file again: High, or a lossless target such as WAV or PNG.
- There is an upload limit: Small first; go up only if the result looks or sounds wrong.
- The source is already heavily compressed: High will not bring detail back. It only makes the file larger.
More guides
How in-browser conversion works, and how to check that nothing is uploaded
What happens to a file when you convert it on SnapConvert, the limits of converting in a browser tab, and a one-minute check you can run yourself.
MOV vs MP4: what is different and when to convert
Why iPhone videos are MOV files, why they sometimes fail to upload or play, and what converting to MP4 changes.
MP3, M4A, FLAC, WAV or OPUS: choosing an audio format
How the common audio formats differ in size, quality and compatibility, with file sizes per minute and advice on what converting can and cannot fix.
PNG, JPG, WEBP or AVIF: which image format to use
When each image format is the right choice, what happens to transparency when you convert, and why some upload forms still reject WEBP.
Making a GIF from a video without ending up with a huge file
Why GIFs are so large, what the three quality settings produce, and when a short MP4 is the better choice.
Getting the audio out of a video: MP3, M4A or WAV
How to save only the soundtrack of an MP4, MOV, MKV or WEBM file, which audio format to choose, and how large the result will be.
Making a video small enough to send
What decides the size of a video file, what the Small setting changes and what it leaves alone, and the options when the result is still too big.
MKV, AVI, WMV, FLV and other video formats: what they are and what converting to MP4 keeps
Where MKV, AVI, WMV, FLV, 3GP, MPG and TS files come from, why they fail to play, and what is kept and dropped when you convert them to MP4.
WEBM vs MP4: which to use and when to convert
Why screen recorders and browsers produce WEBM, where WEBM does not play, and what converting in either direction does on this site.
Making a favicon: PNG or JPG to ICO
How to prepare an image for a favicon, exactly what the ICO file from this site contains, and the HTML needed to use it.
Converting several files at once, and what the error messages mean
How the file queue works, the ways to add files, and what each error message on SnapConvert means and how to get past it.
Are online file converters safe? What happens to a file you upload
What a server-based converter can see and keep, which files should not be uploaded, the warning signs of a bad converter site, and the alternatives that keep a file on your own device.
Turning an iPhone voice memo into an MP3
How to get a recording out of the Voice Memos app, convert the M4A file to MP3 or WAV on the phone or a computer, and when you do not need to convert at all.
Converting a WhatsApp voice message to MP3
Where WhatsApp keeps voice messages, why they are OPUS or OGG files that many apps will not open, and how to turn one into an MP3 without uploading it.