FLAC to MP3 file size: a real comparison table
A 3-minute CD-quality track is about 30 MB raw, lands near 16 MB as FLAC, and 2.9–7.2 MB as MP3 depending on bitrate. Here is the concrete table, then how the numbers are worked out.
In 30 seconds
FLAC keeps the file large (roughly half the raw size); MP3 shrinks it to a fraction. For one 3-minute song: FLAC ≈ 16 MB, MP3 128 ≈ 2.9 MB, 192 ≈ 4.3 MB, 256 ≈ 5.8 MB, 320 ≈ 7.2 MB. A 12-track album follows the same ratio — FLAC ≈ 260 MB, MP3 192 ≈ 65 MB. Convert at 192 for everyday use, 320 when you want it closest to the original.
One 3-minute stereo track (CD quality: 44.1 kHz, 16-bit)
| Format | Approx. size | vs raw |
|---|---|---|
| Raw (WAV/AIFF) | ~30 MB | 1.0× |
| FLAC (lossless) | ~16 MB | ~0.55× |
| MP3 128 kbps | ~2.9 MB | ~0.10× |
| MP3 192 kbps | ~4.3 MB | ~0.14× |
| MP3 256 kbps | ~5.8 MB | ~0.19× |
| MP3 320 kbps | ~7.2 MB | ~0.24× |
A 12-track album (about 45 minutes total)
| Format | Approx. size |
|---|---|
| Raw (WAV/AIFF) | ~475 MB |
| FLAC (lossless) | ~260 MB |
| MP3 192 kbps | ~65 MB |
| MP3 320 kbps | ~108 MB |
How these numbers are worked out
The raw size is fixed by the audio: 44,100 samples per second × 16 bits × 2 channels ≈ 1.41 megabits per second, or about 10.6 MB per minute. FLAC compresses that losslessly to roughly half, depending on how dense the music is. MP3 size is simply bitrate × time: a 192 kbps track uses 192,000 bits each second, so a 180-second song is 192,000 × 180 ÷ 8 ≈ 4.3 MB. That is why the table rows line up the way they do — it is arithmetic, not a guess.
Which size should you aim for
- 128 kbps — smallest, fine for earbuds and car radios, but the weakest on revealing gear.
- 192 kbps — the balanced everyday choice; most listeners never notice the difference from the original.
- 256 / 320 kbps — closest to the FLAC; pick these when the copy goes on good headphones or a real stereo.
Why converting in your browser fits this
Because the conversion runs on your device, you can keep the FLAC as your master and make several MP3 copies at different bitrates — a small 128 for the phone, a 320 for the stereo — without uploading your music to any server. Re-run a file as many times as you like, at no cost, and pick the size that suits each device.