Why convert FLAC to MP3?
FLAC is lossless, which makes it ideal for keeping your music library, but many car stereos, older MP3 players, smart speakers and apps still refuse it. A three-minute CD-quality FLAC is typically 16–22 MB, while the same song as a 256 kbps MP3 is about 5.8 MB, so a whole album fits where three or four FLAC tracks did.
Converting is one-way: MP3 discards detail you cannot get back. Keep your FLAC files as the master copy and treat the MP3s as portable copies you can always regenerate.
Choosing a bitrate: 128, 192, 256 or 320 kbps
- 128 kbps: 0.96 MB per minute (about 2.9 MB for a 3-minute song) — speech, background listening.
- 192 kbps: 1.44 MB per minute (4.3 MB) — good for most music on earbuds.
- 256 kbps: 1.92 MB per minute (5.8 MB) — the default, a safe choice for music.
- 320 kbps: 2.4 MB per minute (7.2 MB) — the MP3 maximum, for critical listening.
The encoder here writes constant-bitrate plain stereo (no joint stereo), which is slightly less efficient than desktop LAME at the same bitrate. That is why 192 kbps or higher is recommended for music, and why 256 kbps is the default.
Tags and album art from FLAC to MP3
FLAC stores tags as Vorbis comments and the cover as a PICTURE block. The converter maps TITLE, ARTIST, ALBUM, ALBUMARTIST, TRACKNUMBER/TRACKTOTAL, DISCNUMBER, DATE, GENRE and COMMENT to the matching ID3v2.3 frames and copies the front cover into an APIC frame.
Text is written as UTF-16, the ID3 encoding that Windows Explorer, iTunes and most car stereos display correctly for Korean, Japanese, Chinese and accented Latin titles. Turn off "Keep tags and cover art" if you want files without metadata.
What happens to 24-bit and 96 kHz FLAC?
MP3 supports sample rates up to 48 kHz. A 96 or 192 kHz FLAC is resampled to 48 kHz and an 88.2 or 176.4 kHz FLAC to 44.1 kHz before encoding, which keeps the conversion to a simple ratio; 44.1 and 48 kHz files keep their rate. The result card shows both rates.
Bit depth does not carry over to MP3: the encoder works from the decoded signal and the format has no bit-depth setting. A 24-bit FLAC therefore gives the same MP3 as a well-made 16-bit version of the same master.
Converting a whole album, with exact track lengths
Select or drop all of an album's tracks at once and every track is converted in turn while encoding runs in parallel; the ZIP keeps the track names. On a desktop Chrome, encoding runs at roughly 35–45 times real time per worker, so a one-hour album takes one to two minutes.
Every MP3 encoder adds about 1,100 samples (25 ms) of delay at the start and padding at the end. This converter writes a LAME header with the exact values, so players that read it — Chrome, Firefox and most music apps — play each track at the source's exact length and live or classical albums stay gapless.