What is a WAV file?

WAV is a container: a wrapper that holds streams encoded by something else. It is used for editing and archiving.

The extension is .wav, and the full name is Waveform Audio. Both matter less than what the file can hold, which is what the rest of this page is about.

Microsoft published it in 1991. The specification is RIFF WAVE.

A format that has been readable for that long is a format worth trusting with something you want back in ten years.

It is written down and implementable, though the vendor decides what the next version looks like. In practice that is enough for the file to keep opening; it is not enough to be sure of it.

WAV stores its content exactly. Saving it again changes nothing, so it can be opened, edited and re-saved as often as you like without accumulating damage — which is what makes it a working format rather than a delivery one.

Up to 32 bits per channel.

More than eight bits per channel is what stops a gradient from stepping when it is edited, which is why it matters in a working file and rarely in a finished one.

It usually holds PCM. This is the distinction behind most "why will this not play" questions: two files with the same extension can contain entirely different encodings, and a player that refuses one may be perfectly happy with the other.

It also explains why changing container is often fast and lossless while changing codec is neither. Moving the same stream into a different box rewrites the box; re-encoding rewrites the picture.

Up to 65535. Two covers stereo and is what almost everything is; more than two is surround, and it is the part most likely to be folded down when converting to a format that does not define it.

Audacity, Adobe Audition and Reaper read it, and so do most programs of the same kind.

If a file will not open, the format is rarely the problem — it is more often that the program predates it. Converting to something older is the reliable way past that, and it is what the rest of this site is for.

Every current browser reads it.

That makes it a safe thing to put on a page or attach to a message without wondering what the other end has installed.

WAV can hold document properties.

Whether any of it survives a conversion depends entirely on the target, and the honest answer is usually "some of it".

WAV is meant to be opened and changed. Keep the file in this format for as long as the work is going on, and export from it whenever a finished copy is needed.

The recurring complaints: the files are large for what they contain.

None of these is a reason to avoid the format. They are the things worth knowing before you are surprised by one, which is a different claim and a more useful one.

A WAV stores every audio sample as a raw number with nothing applied. CD-quality stereo — 44.1 kHz, 16-bit, two channels — works out at about 10 MB per minute whether the minute holds an orchestra or complete silence. The size depends on duration and settings and on nothing else.

That makes it predictable and makes it enormous. Forty minutes is 400 MB, an hour-long interview is around 600, and a day of field recording is beyond what most people expect to handle. Every practical difficulty with WAV comes from this one property.

WAV uses 32-bit fields to record chunk sizes, which caps a file at 4 GB. At CD quality that is reached at roughly six and a half hours; at 24-bit and 96 kHz it arrives in under two.

Recorders handle the limit by splitting the file, which is why a long session comes back as several numbered parts. Some software instead writes past the boundary and produces a file that plays correctly up to the wall and then reports a wrong length or refuses entirely. RF64 and BWF extend the format to remove the cap, and they are what professional recorders write for long-form work — but a plain `.wav` still has it.

WAV is a RIFF container and can in principle hold compressed audio — there are legacy codecs that could be stored inside one. In practice essentially every WAV in existence is uncompressed PCM, which is why the format is treated as a synonym for uncompressed audio.

Very occasionally a file from old Windows software turns out to hold something else and refuses to play in a modern editor. It is rare enough to be a curiosity rather than a caution, and the symptom is distinctive: a `.wav` that one program opens and another calls unsupported.

Sample rate sets how often the signal is measured — 44.1 kHz for CD, 48 kHz for video work, 96 or 192 for high-resolution recording. Bit depth sets how precisely each measurement is stored: 16 bits gives 65,536 levels, 24 gives about 16.7 million.

For recording, 24-bit is the setting worth using and the reason is headroom rather than audible quality. It leaves room to record conservatively and lift the level afterwards without the noise floor rising to meet you. Going above 48 kHz multiplies the file size for a benefit that controlled listening tests have not reliably demonstrated.

Audio editors, transcription tools, speech-recognition pipelines, forced-alignment software and a great deal of research tooling accept WAV and refuse compressed formats. The reason is not fidelity — it is that reading raw samples needs no decoder, which removes an entire class of bugs and dependencies from their code.

This is why converting an MP3 to WAV is a legitimate and common operation despite restoring nothing. The file becomes ten times larger and contains exactly the audio the MP3 contained; what it gains is being acceptable to a program that would otherwise reject it.

A WAV made from an MP3 has the size of an uncompressed file and the content of a compressed one. The audio the MP3 encoder discarded is gone, and no format brings it back — the WAV faithfully stores what remains.

Worth saying plainly because the reverse belief is common. WAV is the right destination for software that demands it and the wrong one for improving a file. If quality is the goal, the only answer is going back to a better source, and if none exists then none exists.

WAV has no real tagging convention. Some tools write a small INFO chunk with a title and artist, most write nothing, and support for reading any of it is inconsistent. A music player will usually show the file name and little else.

Broadcast WAV — BWF — added a structured chunk for origination details and timecode, and it is what professional recorders write. For an ordinary WAV, expect the file to arrive unlabelled and plan on tagging after converting to something that has a proper place for it.

A great many WAVs are stereo files carrying one microphone duplicated across both channels — conference recordings, phone memos, single-source interviews. That doubles the size to say the same thing twice.

Converting such a file to mono halves it with no loss of anything real, and for speech destined for transcription it is strictly better. Keep stereo for music, for anything with a genuine stereo field, and for recordings with two people on separate channels.

MP3 or AAC when the file needs to move — email, upload, a phone, a car. Expect about a tenth the size; use 128 kbps for speech and 192 or higher for music. FLAC when nothing may be lost but the size is impractical: it is lossless, gives back exactly the same samples, and lands at roughly half.

FLAC is the answer people usually want and rarely consider. A 600 MB interview becomes about 300 MB with every sample intact, which is a better trade than either keeping the WAV or accepting lossy compression. Because the conversion runs in your browser, the recording is never uploaded — which matters given that what people convert here is overwhelmingly interviews, meetings and voice notes.