Bulk Audio Converter

About converting audio in bulk

A folder of WAV recordings from a studio, a year of iPhone voice memos in M4A, an album in FLAC that your car will not play — converting them one at a time is slow and boring.

This tool converts all of them at once. Drop the files in, pick the format, press one button, and get every file back converted in a ZIP. Each file also gets its own player and download button, so you can listen before you save.

How to use it

• Click Click to upload, or drop many audio files onto the box
• Pick the format: MP3, M4A, WAV, FLAC or OGG
• Choose the quality — 192 kbps is a good default, 320 for music
• Press Convert them all — the first run downloads the audio engine
• Click Download all (ZIP), or save single files from the list

Popular conversions

• WAV to MP3 — make big studio or voice recordings about a tenth of the size
• M4A to MP3 — iPhone voice memos and iTunes files for any player
• FLAC to MP3 — lossless music for a phone, a car or an old MP3 player
• MP3 to WAV — when an editor or a DJ program needs WAV
• WAV to FLAC — keep perfect quality at about half the size
• OGG to MP3 — game sounds and web audio for everyday apps

You can mix different formats in one batch; every file comes out in the format you choose.

Which format to choose

• MP3 — plays everywhere: cars, phones, old players, every app
• M4A (AAC) — a little better than MP3 at the same size; best for Apple devices
• WAV — uncompressed and lossless; very large files, for editing
• FLAC — lossless like WAV, but about half the size; for archives and music collections
• OGG — open format for games and web projects

A higher bitrate cannot add quality that was not in the original. Converting MP3 to WAV makes the file bigger but does not make it sound better.

Everything happens on your device

The converter is a real audio engine (ffmpeg) compiled to WebAssembly and run inside your browser:

• Private — recordings, interviews and unreleased music are never uploaded
• No upload wait — even a large batch starts at once
• Free — no sign-up, no watermark, no file count limit

The engine is about 30 MB and downloads once, the first time. It then converts the whole batch, one file after another. You can switch to another tab while it works — just keep this tab open.

Frequently asked questions

How do I convert multiple audio files at once?

Drop all the files onto the box, pick a format such as MP3, choose the quality, and press Convert them all. Each file is converted in turn and you download them together as a ZIP.

How do I convert many WAV files to MP3?

Drop the WAV files in, leave MP3 selected, choose 192 or 320 kbps, and press Convert them all. Each MP3 is about a tenth of the size of its WAV.

Are my files uploaded?

No. The audio engine runs inside your browser, on your own device. Your files never leave your computer.

Why does the first conversion take longer?

The audio engine (about 30 MB) downloads once. Your browser keeps it, so the next batch starts faster.

Will the file names stay the same?

Yes. Only the ending changes, for example interview.wav becomes interview.mp3. If two files would get the same name, the second one gets a number added.

What happens if one file fails?

That file is marked in the list and skipped, and the rest of the batch continues. Damaged files and copy-protected music (old iTunes .m4p files) cannot be converted.

Good to know

• Up to 200 files per batch, converted one at a time
• Video files work too — only the sound is kept
• Song tags like title and artist are kept where both formats support them
• Very long files use a lot of memory; a computer handles them better than a phone

Related tools

• WAV to MP3 — one file, with a player before you download
• M4A to MP3 — for iPhone voice memos
• Audio Converter — one file, any format
• Audio Merger — join the converted files into one
• MP3 Tag Editor — set the title, artist and cover art
• Bulk Image Converter — the same for images