Audio Converter
A batch audio converter: load MP3, WAV, M4A, OGG or FLAC in any mix, queue as many as you like, and write M4A, WAV, Opus or FLAC back out with a zip at the end.
The track
Track
Drop audio here
MP3, WAV, M4A, OGG or FLAC · one track or a whole folder
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Files to convert
Converted
Pick audio and this says how much of it there is and where it can land. One track or a folder: the same strip, the same four formats.
Running a batch
- Drop your files or a folder on the Track box, or choose them. MP3, WAV, M4A, OGG and FLAC can sit in the same pick.
- Read the queue, which shows up as soon as there are two or more files. Every row carries a name, a type, a size and what it lands as, and its remove button drops that file before any work starts; down to one file, the page goes back to the single track.
- Choose the output format. M4A is selected the first time and your pick is remembered; Opus for the smallest files, WAV for editing, FLAC for a lossless archive.
- Press Convert all. A single file gets Convert instead, then plays back in the same well before Download.
- Save each result from its row, or use Download all (.zip) once at least two have finished.
About this tool
An audio converter earns its keep on the day something refuses to open your file. Load MP3, WAV, M4A, OGG or FLAC and there are four outputs to pick from. M4A is selected by default because it plays on everything and stays small. Opus goes smaller again at the same quality. WAV is the uncompressed format editors and voice-over clients tend to insist on, and FLAC keeps every sample while landing near half a WAV's size.
The queue is the reason to open this rather than a single-file tool. Pick twenty files in one go, mixed formats included, and before anything runs each row says what it lands as; with WAV picked that is an exact size, totalled at the top with the minutes of audio. Press Convert all and each row finishes with its own download, its new name and its size. A file your browser cannot decode fails on its own row while the rest carry on. Cancel stops the file in flight and keeps what finished, and Download all (.zip) collects them into converted-audio.zip. One file on its own plays in a single well, original and converted, before you save it.
A handheld recorder full of WAVs
Twelve talks came off a field recorder as WAV, a little over 400 MB together, which is roughly 35 minutes of stereo audio and more than any mail server was going to accept. Select all twelve at once, leave the format on M4A, press Convert all. Rows turn over one at a time, each showing its new size beside the old one.
AAC at its default rate brought that down to something near 30 MB, well under the 300 MB ceiling the zip button works to, so Download all (.zip) handed the lot back in one archive. Filenames carry across the conversion: talk-03.wav returns as talk-03.m4a.
Good to know
- MP3 goes in but never comes back out. There is no permissively licensed MP3 encoder I can ship, so the compact outputs here are M4A (AAC) and Opus, both of which play anywhere MP3 does.
- Every file is decoded into memory in full before it is re-encoded. What strains an older phone is the length of your longest lossless file, not how many rows are waiting. The zip is offered up to roughly 300 MB of converted audio; past that, take the files from their rows.
Frequently asked questions
Can I convert a folder of mixed formats in one go?
Yes. Each file is decoded independently before it is re-encoded, so a pile of MP3s sitting next to WAVs and FLACs all arrive in the same output format from a single run.
Why is there no MP3 output?
MP3 encoding wants a licensed encoder, and bundling one is not something I want to do. M4A (AAC) covers the same ground: the same players open it and the file is usually smaller at matching quality. MP3 input decodes fine, so mp3 to wav and mp3 to m4a both work.
What happens if one file in the batch fails?
It stops at that row and nowhere else. The row says it couldn't be read and is left out of the zip, the queue moves to the next file, and a caution above the controls names every file that failed. Cancel behaves differently: the files that finished stay in Download all, and the one in progress and everything after it are marked canceled.
Does converting to WAV improve a compressed file?
Nothing that was thrown away comes back. Decoding an MP3 gives you the samples the original encoder left behind, and WAV then stores exactly those at a much larger file size. Convert to WAV because a program demands it, not to repair quality.
How much smaller is FLAC than WAV?
Roughly half for typical music, less for dense loud material, and lossless either way. Both formats decode to identical samples. FLAC packs them tighter, which is why it suits an archive while WAV suits an editor.
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