OneTaskBy Tim King · Updated
FLAC to MP3 Converter
128, 192 or 320 kbps Bitrate Choice for Lossless Music in a Portable File
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How the FLAC To MP3 works
Drop in a FLAC file and download an MP3 at 128, 192 or 320 kbps. This FLAC to MP3 converter decodes the lossless audio with your browser's built-in FLAC decoder and encodes it with an open-source MP3 encoder in the same tab. Nothing is uploaded, so large albums stay on your disk.
FLAC to MP3: lossless master to lossy copy
FLAC is lossless compression. It shrinks audio to roughly 50 to 70% of the WAV size, and decoding it gives back every sample exactly. MP3 is lossy: it gets files far smaller by discarding detail a psychoacoustic model predicts you will not notice. Converting FLAC to MP3 is the cleanest transcode there is, because only one generation of loss happens. Keep the FLAC as your archive and make MP3s for phones, cars and players that cannot read FLAC.
What is lost going from FLAC to MP3
- High frequencies. LAME low-passes around 19.5 kHz at 320 kbps and lower at smaller rates, around 17 kHz at 128 kbps.
- Bit depth and hi-res rates. A 24-bit, 96 kHz FLAC is decoded at your browser's audio rate, usually 44.1 or 48 kHz, and MP3 has no fixed bit depth. The extra resolution is not carried.
- Transient detail. Low bit rates can smear sharp sounds such as castanets or hi-hats.
- Tags. Vorbis comments and embedded artwork in the FLAC are not copied to the MP3.
At 320 kbps, blind listening tests rarely find a difference from the FLAC on ordinary equipment. At 128 kbps the file is a fifth of the size and the loss is easier to hear.
Browser support for FLAC decoding
FLAC decodes natively in Chrome and Edge from version 56, Firefox from 51, Safari 11 and later on macOS and iOS, Opera and Samsung Internet. Very large 24-bit, 192 kHz files work but need plenty of memory, because the whole track is decoded into the tab before encoding.
How to read the stats
Source shows the decoded channels, rate, length and the FLAC's file size. Output is the MP3 bit rate and Output size estimates the MP3, roughly bit rate × seconds. A four-minute song is about 9.2 MB at 320 kbps and 3.7 MB at 128 kbps.
For a lossless editable copy use FLAC to WAV. WAV to MP3 and OGG to MP3 cover other sources.
FAQ
Which MP3 bit rate is best for FLAC files?
Choose 320 kbps if storage is not a concern; it is the closest MP3 gets to the lossless source. 192 kbps is a good balance for phones, and 128 kbps suits spoken word or tight storage. The size line updates as you switch between them.
Does FLAC to MP3 lose quality?
Yes, once. MP3 is lossy, so detail is discarded during encoding. Because FLAC is lossless there is no earlier generation of loss to compound, which makes this the best-case transcode. Keep the FLAC if you might want another format later.
Can I convert a 24-bit or 96 kHz FLAC?
Yes. The browser decodes it at its own audio rate, usually 44.1 or 48 kHz, and the MP3 is encoded from that. MP3 cannot store 96 kHz audio anyway, so nothing that the MP3 could have kept is lost by the resample.
Is my FLAC uploaded anywhere?
No. The file is decoded, processed and encoded inside your browser with the Web Audio API. Nothing is sent to a server, so it works offline once the page has loaded and your audio stays private.
See also: all Audio & Video tools, Units, Images, Documents, Data & Code.
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