How do I convert MP3 to FLAC?

Add your MP3 file to the upload area above, then press Convert. The FLAC file downloads straight to your device. You do not need an account, and there is no watermark.

Are my files uploaded to a server?

No. This conversion runs entirely inside your browser using WebAssembly, so the file never leaves your device — you can even disconnect from the internet after the page loads and it will still work.

Does converting to FLAC reduce quality?

No. FLAC is a lossless format, so the conversion preserves exactly what is in your MP3 file. Note that it cannot recover detail that was already discarded when the MP3 was first created — a lossless container does not undo earlier compression.

How large a file can I convert?

Up to 300 MB per file for this conversion. Because the work happens in your browser, the practical limit is your device's memory — larger files work on a desktop with plenty of RAM and may fail on an older phone.

Can I convert several files at once?

Yes. Add as many as you like and press Convert All. Each file is processed independently, so one failure does not stop the rest, and you can download everything together as a ZIP.

Can I use this on my phone?

Yes. FileTools360 works in mobile browsers on iOS and Android, including choosing files straight from your camera roll. Very large videos may run out of memory on a phone — those are better converted on a laptop.

AudioLosslessRuns in your browser

MP3 to FLAC Converter

Turn MP3 files into FLAC in a couple of clicks. The universal lossy audio format. Lossless compression — CD quality at roughly half the size. The conversion is lossless — every pixel, sample or byte in the source is preserved.

On your deviceNever uploadedGone when you close the tabHow this works

Drop your files here

MP3 files (.mp3) · up to 300 MB each

or paste files from your clipboard

Ready when you are

Drop a MP3 file above and FileTools360 will turn it into FLAC — right here on your device, without uploading anything.

⌘K to search converters

How to use it

1
Add your MP3 files
Drag them onto the upload area, choose them from your device, or paste them from your clipboard. You can queue several at once.
2
Adjust the settings if you want to
The defaults suit most people. Open Advanced to control bitrate, sample rate and channels and start and end times.
3
Convert and download
Press Convert. Everything happens on your own device — nothing is uploaded. Download files one by one, or grab them all as a ZIP.

MP3 and FLAC explained

MP3 is the lossy audio format that made digital music portable. Its patents expired in 2017, which is part of why it remains ubiquitous — anyone can implement it freely.

FLAC compresses audio losslessly, typically to about half the size of WAV. Decompressed, it is bit-for-bit identical to the original — the compression is mathematical, not perceptual.

Where MP3 files come from: Music libraries, podcasts and voice recordings.
Where FLAC is used: Hi-fi music libraries and archival rips of physical media.

MP3 vs FLAC

The two formats solve different problems, which is why converting between them involves trade-offs rather than a straight upgrade.

MP3 compared with FLAC
Property	Source	Target
Compression	Lossy	Lossless
Introduced	1993	2001
Browser support	Plays absolutely everywhere.	Great on desktop and Android; iOS support is newer.

MP3 is stronger at: Plays on absolutely everything, including old hardware. Small files. No licensing constraints since 2017.
FLAC is stronger at: Lossless — provably identical to the source. Roughly half the size of WAV. Rich metadata and cover art support.

Why convert MP3 to FLAC?

People make this switch when they run into the limits of MP3: archiving masters, or editing audio you will re-export repeatedly. FLAC is the better fit when archiving music you may want to re-encode later, or storing CD rips.

MP3 limitations that prompt the switch: Lossy — discarded detail cannot be recovered. Beaten on quality-per-byte by AAC and Opus. No native support for multichannel audio in practice.
What you give up: Much larger than MP3 or AAC. Not supported natively by all portable devices.

Does converting MP3 to FLAC reduce quality?

Going from MP3 to FLAC moves already-compressed data into a format that stores it exactly. Nothing is lost from this point on, but nothing is recovered either — the detail MP3 discarded when the file was first created is gone permanently. Expect a noticeably larger file for identical visual quality.

Converting MP3 to a lossless format like FLAC does not restore quality. It produces a larger file containing exactly the same degraded audio.