WAV → FLAC
WAV to FLAC converter
WAV PCM is compressed losslessly into FLAC. Decoding the FLAC returns the exact original samples, verified by an internal MD5 checksum. Typical files end up 40–60% smaller.
…or drag files and folders here. Add as many as you like — everything is processed on this device.
.aif .aifc .aiff .caf .flac .wav .wave
In one paragraph
This is the conversion to run on any WAV archive. FLAC stores identical audio in roughly half the space, adds proper tagging and cover art that WAV never handled well, and detects corruption because it checksums its own contents. There is no quality argument against it — the only reason to keep WAVs is software that cannot read FLAC.
Sonic Batch encodes with the native FLAC encoder in its self-hosted engine and lets you choose the compression level. The level affects encoding time and file size only; the decoded audio is bit-identical at every setting.
Does this change the audio quality?
Genuinely lossless when the bit depth matches the source. FLAC supports 16 and 24-bit; a 32-bit float WAV must be converted to 24-bit integer, which is a real (if inaudible) change and is reported per file.
- Match the bit depth to the source to stay bit-exact. 32-bit float WAVs are written as 24-bit.
- Very noisy or heavily limited material compresses less — expect 70–80% rather than 50%.
- Some older hardware and broadcast systems still cannot read FLAC. Check before deleting the WAVs.
A worked example
Archiving a folder of session recordings
- Drop the WAV files in — the panel reports bit depth and sample rate for each.
- Set the bit depth to match the source (24 for most session recordings).
- Set compression level 8 for the smallest files; level 5 if you are converting hundreds and want it faster.
- Convert all and download the ZIP. The manifest records the size saved on every file.
Compression level 8, bit depth matching the source
Levels 0 through 12 all decode to identical audio; higher levels simply search harder for a compact representation. Level 8 is the highest widely-supported setting and gives about 2–3% more saving than the default level 5 at several times the CPU cost. If you are batching an entire archive, level 5 is a reasonable compromise. Never lower the bit depth for archiving.
Supported formats, limits and browser notes
Sonic Batch decodes with the browser when it can (faster, no engine download) and falls back to the self-hosted WebAssembly engine when it cannot. Every combination below works in every listed browser; the column only tells you which decoder does the work.
| Input | What it is | Chrome | Firefox | Safari | iOS |
|---|---|---|---|---|---|
| WAV | Raw PCM samples with a small header. Perfect fidelity, roughly 10 MB per stereo minute. | Native | Native | Native | Native |
| AIFF | Apple’s uncompressed PCM format — the WAV equivalent for Logic and Pro Tools. | Partial | Partial | Native | Native |
| FLAC | Lossless compression, typically 50–60% of WAV size, bit-identical when decoded. | Native | Native | Native | Native |
| CAF | Apple container used by older iOS Voice Memos. Usually holds ALAC, IMA4 or raw PCM. | Engine | Engine | Partial | Partial |
| Output | Encoder | Bitrates / depth | Sample rates | Tags |
|---|---|---|---|---|
| FLAC | flac | 16, 24-bit | 8–96 kHz | Yes + artwork |
- Max per file
- 400.0 MB
- Max per queue
- 4.00 GB
- Max duration
- 4:00:00
- Max archive
- 1.50 GB
These are enforced ceilings, checked before any decoding starts, not measured maximums — a file over the limit is rejected rather than allowed to exhaust the tab’s memory. Real-world capacity is lower on older phones, which is why the scheduler runs one file at a time on iOS and Safari.
Where your audio goes
Nowhere. Your file is read from disk into this browser tab with the File API, decoded and encoded by code running in that same tab, and handed back to you as a download. It is never transmitted.
That is a structural property of the application, not a policy promise: there are no API routes, no server actions and no third-party processing services in this project, so there is nothing capable of receiving a file. The page’s Content-Security-Policy also restricts connections to this origin, and the automated test suite includes a browser test that fails if any network request during import, preview, conversion or download carries media bytes.
The trade-off, stated plainly:results live in your tab’s memory until you download them. Closing or reloading the page discards them. There is nothing on a server to recover, because nothing was ever put there.
Troubleshooting
The FLAC is only slightly smaller than the WAV.
Compression depends on the material. Dense, loud, heavily limited masters have little redundancy left to exploit. Sparse acoustic recordings often halve.
My 32-bit float WAV became 24-bit.
FLAC has no 32-bit float mode. The conversion to 24-bit integer is flagged in the file warnings. For float archives, keep the WAV.
A large file was rejected.
The 400 MB per-file budget stops the tab running out of memory. Split long recordings, or convert them in a desktop tool where memory is not constrained by a browser tab.
Frequently asked questions
Is WAV to FLAC lossless?
Yes. FLAC decoding returns the exact input samples, and the encoder stores an MD5 of the audio so any corruption is detectable later.
How much space will I save?
Typically 40–60% for music. Spoken word and sparse recordings save more; loud, dense masters save less.
Will I lose my metadata?
No — FLAC handles tags and cover art better than WAV does. Set fields in the metadata controls if the WAV had none.
Can I convert back to WAV later?
Yes, and the result is bit-identical to the WAV you started with, provided the bit depth matched.