AudioConverter Help

Open the converter

Convert audio files, or pull the audio out of videos, right in your browser. Free. Nothing you convert ever leaves your computer.

What it does

AudioConverter turns audio files from one format into another: WAV to MP3, FLAC to M4A, WMA to OGG, and so on. Drop in a video and it pulls the sound out as an audio file. Drop in a whole folder and it converts everything inside, including subfolders.

Think of it as a universal adapter for sound files. You pick the plug you want on the other end, drop your files on it, and press one button.

The whole thing runs inside your browser. The first time you open it, your browser downloads the conversion engine (about 31 MB, a build of the open-source FFmpeg). After that it is cached, and every conversion happens on your own computer. No upload, no waiting on a server, no file-size fees.

Privacy

Your files never leave your computer. There is no server that receives them. You can check this yourself: open your browser's network tab while converting and you will see no uploads.
We ask for your first name and email once, the first time you open the tool on a browser. We might reach out with a question about how to improve the tool, or to mention other cool tools we build. We will never give your email address to anyone else.
Your settings (chosen format, quality, and so on) are remembered in your browser only.

Quick start

Open the converter. Wait for the engine banner at the top to disappear (first visit only).
Drop audio or video files onto the big dashed box, or click Browse files. On Chrome or Edge you can also drop a whole folder or click Browse folder.
Pick the output format in Convert to. Adjust quality if you like. The defaults are sensible.
Keep dropping files if you have more. Nothing starts until you press the button.
Press Convert all. Each row shows a progress bar, then where the file was saved and how big it is.

Press Stop to halt after the current file. Remove takes a file out of the queue. Clear empties it. If a file fails, a Copy error button puts the technical details on your clipboard so you can send them to us.

Formats

You can convert to

Format	Good for	Notes
MP3	Plays everywhere	Bitrate 64 to 320 kbps, or VBR quality levels. Keeps tags and cover art.
M4A (AAC)	Apple devices, small files	Better than MP3 at the same size. Keeps tags and cover art.
WAV	Editing, archiving, maximum compatibility	Uncompressed. 16, 24 or 32-bit. Large files.
FLAC	Lossless archiving at about half the size of WAV	16 or 24-bit. Keeps tags and cover art.
M4A (ALAC)	Lossless for Apple devices	16 or 24-bit.
OGG (Vorbis)	Games, open-source players	Bitrate or quality levels.
OPUS	Voice, podcasts, smallest files	Excellent at low bitrates. 48 kHz.
AIFF	Mac audio software	Uncompressed, like WAV.
WMA	Older Windows players
AC3 (Dolby Digital)	Home theatre, DVD authoring	Up to 5.1 channels.
WavPack	Lossless, compact	16 or 24-bit.
Same as source	Fixing a damaged file, forcing new settings	Re-encodes into the same type. Output gets a suffix so it never overwrites the original.

You can convert from

Audio: MP3, WAV, FLAC, OGG, OPUS, AAC, M4A, M4B, M4R, WMA, AIFF, APE, WavPack, Musepack, AC3, E-AC3, DTS, AU, CAF, AMR, GSM, Speex, MP2, MP1, MKA, WEBA, TTA, TAK, Shorten, VOC, RealAudio, and For The Record court recordings (TRM, FTR).

Video (audio is extracted): MP4, M4V, MOV, MKV, WEBM, AVI, WMV, ASF, FLV, MPG, MPEG, VOB, 3GP, TS, M2TS. If a video has several audio tracks, the first one is used.

Options

Setting	What it does
Quality	For lossy formats. Higher bitrate means better sound and a bigger file. 192 kbps MP3 or 160 kbps AAC is transparent for most music. VBR lets the encoder spend bits where the music needs them.
Bit depth	For WAV, AIFF, FLAC, ALAC, WavPack. 16-bit is CD quality and right for almost everything. Use 24-bit only if the source is 24-bit.
Sample rate	Keep leaves it as the source. 44.1 kHz is CD, 48 kHz is video. Lower rates make smaller files for voice recordings.
Channels	Keep, Mono, or Stereo. Mono halves the size of a voice recording with no real loss.
Add to name	Text appended to every output name, for example `_converted`. Leave empty to keep the original name with the new extension.
Keep tags	Copies title, artist, album and the rest into the new file when the format supports it.
Keep cover art	Carries embedded album art into MP3, M4A and FLAC outputs.

Where converted files go

Dropped a folder, or used Browse folder (Chrome or Edge): the converted file is written right beside the original, in the same folder. Your browser asks once for permission to save there. If a file with that name already exists, the new one gets _1, _2 and so on. Originals are never touched.
Dropped loose files, or used Browse files: the converted file goes to your browser's Downloads folder. A web page cannot know which folder a loose file came from.

Each row in the queue shows which of the two happened. Hover a file name to see it.

Court recordings (For The Record, TRM and FTR files)

Courtrooms that use For The Record produce .trm files: about five minutes each, four separate microphone channels, in a format ordinary players cannot open. AudioConverter reads them directly.

When a TRM file is in the queue an extra row of options appears:

Channels	Result
All channels in one file	One file with all four (or however many) microphones as separate channels. Best for WAV or FLAC when you need to isolate a speaker later in an audio editor.
Stereo mix	Every microphone blended into an ordinary stereo file. Best for listening or transcription. Each mic is mixed at equal level.
One file per channel	A separate file for each microphone, named `_ch1`, `_ch2` and so on.

Join chunks of the same session is on by default. Drop a whole day of recordings and the tool sorts the chunks into sessions by courtroom and time, then produces one continuous file per session instead of dozens of five-minute pieces. A break of more than 15 minutes starts a new session. Joined files are named Courtroom_Date-Time_joined. Turn the checkbox off to get one output per chunk.

A full day of court audio is a lot of data to hold in a browser tab. If you are joining more than about 30 chunks at once, pick a compressed output (MP3, Opus, M4A) rather than WAV, and close other heavy tabs.

Limits and known gaps

Not available as output: AMR, APE, Musepack, GSM, DTS. The browser engine can read them, but cannot write them.
Dictation recorder formats (DSS, DS2, DVF, MSV) are not supported. No open decoder exists for them.
Audio CDs cannot be ripped from a browser.
Very large files: the browser engine works in a memory space of about 2 GB, and phones have far less. Multi-hour lossless files may fail. Video files are fine because only the audio track is read.
Folder drop and save-beside-original need Chrome or Edge. Firefox and Safari still convert, but always save to Downloads.
First load downloads about 31 MB once. On a phone, do that on Wi-Fi.

FAQ

Is it really free?

Yes. There is nothing to install and no limit on how many files you convert.

Why does it want my email?

So we can ask how to make it better, and occasionally mention other tools we build. Once per browser, never shared. If you clear your cookies you will be asked again. There is a Sign out link in the footer if you want to test that.

Does converting MP3 to MP3 improve quality?

No. Converting between lossy formats always loses a little. Convert from the best source you have, and use lossless formats (WAV, FLAC) when you plan to edit further.

The first file is slow, then the rest are fast. Why?

The engine has to start up once. After that a five-minute song converts in a second or two.

Can I use it offline?

After the first visit, yes. The page and the engine are cached. Chrome and Edge also let you install it as an app from the address bar.

Something failed. What do I send you?

Press the Copy error button on the failed row and paste the result into your email, along with what kind of file it was.