In this guide
Choose an audio format for the task and the recipient's requirements. PCM WAV is a common working format, FLAC provides lossless compression, and MP3 or AAC can make smaller lossy listening copies. A file extension alone does not prove the codec or source quality.
For the distinction between file format and delivery resolution, see what high-resolution audio means.
The right audio file format depends on what you need to do with the sound. PCM WAV is commonly used for working copies, FLAC can store losslessly compressed audio, and MP3 or AAC can provide smaller listening files using lossy compression. Check what the receiving app accepts and keep the best available original before converting.
File extensions, containers and codecs are related but not interchangeable. A container organizes media data; a codec describes how audio is encoded and decoded. Some extensions identify packaging that can contain different encodings. MDN's audio codec guide and container guide list common combinations.
Common audio file types compared
| File type | What it commonly contains | Useful for | What to check |
|---|---|---|---|
| MP3 | Lossy MP3 audio, often with metadata. | Widely supported audio-only listening copies. | Another MP3 encode can discard more information; inspect the actual export. |
| WAV | Often uncompressed PCM, although WAV can carry other encodings. | Recording or editing where the destination accepts the specified PCM settings. | Encoding, sample rate, bit depth, channels and size. |
| FLAC | Losslessly compressed audio. | A smaller sample-preserving copy of a compatible PCM source when the destination supports FLAC. | Compatibility and source history; a lossless copy of a lossy source retains the earlier losses. |
| M4A | MPEG-4 audio packaging, often AAC or Apple Lossless. | Audio delivery or listening in compatible apps. | The actual codec and player support; M4A alone does not mean lossless. |
| AAC | Lossy AAC audio, which can use different packaging. | Compressed listening or media workflows that accept the file and profile. | Whether the destination reads its packaging and AAC profile. |
| AIFF | Commonly uncompressed PCM; AIFF-C can use other encodings. | A working or delivery file in a compatible workflow. | Encoding, sample rate, bit depth and destination compatibility. |
| OGG | An Ogg container that may hold Vorbis, Opus or other supported codecs. | Compatible web or application audio workflows. | The codec inside and whether the receiving player supports it. |
These are common uses, not guarantees about every file. For the details of individual types, see WAV, MP3, M4A, AIFF, FLAC and OGG.
Lossy, lossless and uncompressed audio
- Lossy encoding, such as MP3 or AAC, discards some information to reduce data. Another lossy encode can discard more.
- Lossless compression, such as FLAC, can reproduce its encoded sample data without that kind of discard. The Library of Congress FLAC description identifies its PCM input and lossless behavior.
- Uncompressed PCM stores sample values without lossless compression. PCM WAV can be larger, but a larger WAV made from an MP3 cannot restore the MP3's discarded information.
“Lossless” describes the encoding step, not the whole recording's history. If the source was noisy, clipped or previously lossy, changing its format does not undo those problems. Read lossy vs. lossless audio for examples.
Which audio format should you choose?
| Task | Practical starting point | Before sending or using it |
|---|---|---|
| Record and continue editing | Keep the original project and a compatible PCM working export, often WAV. | Match the required sample rate, bit depth and channels; check the saved take. |
| Archive a compatible PCM source | Consider FLAC for lossless compression or retain the original PCM file. | Verify the archive and playback tools support it; keep metadata and backups as needed. |
| Share an audio-only listening copy | Use a format accepted by the recipient, such as MP3 where appropriate. | Compare the actual lossy export with the original and keep the source. |
| Send audio for video | Ask the editor for the accepted format and technical specifications. | Preserve timing and check the file against picture in the destination timeline. |
There is no single “best quality” extension for every task. A clean source, appropriate settings and compatibility matter more than renaming a file or assuming a bigger number guarantees better sound.
How do audio formats affect file size?
For uncompressed PCM, estimate the audio payload as sample rate × bit depth × channels × duration ÷ 8. One minute of 48 kHz, 16-bit stereo PCM is about 11.52 MB of audio data before headers. One minute of constant 192 kbps MP3 is about 1.44 MB of encoded payload before framing and tags. These examples use decimal MB; variable bitrate, metadata and different settings change the result.
For your own settings, use the audio file size calculator. It estimates size rather than measuring quality. Learn how sample rate, bit depth and bitrate differ before choosing an export.
How to convert an audio file
- Check the source and destination. Identify the actual file, its encoding and the format the receiving app requests. Keep the original.
- Choose a compatible converter. The audio converter links supported local workflows. Input format, duration, channel count and output limits differ by tool; check the specific page before starting.
- Prepare and inspect the output. Choose the appropriate format and settings, then preview the file, check its duration and download it. Confirm it opens in the destination app.
- Keep timing and quality in mind. Re-encoding MP3 is lossy and may add delay or padding; resampling or bit-depth changes can alter samples. For synchronized media, compare a cue near the start and another near the end.
If you only need to inspect a supported PCM or floating-point RIFF/WAVE file, the WAV file inspector reads stored format fields locally. It does not inspect every audio format or establish the recording's quality.
Common questions
Is WAV always lossless?
WAV is a container, not a guarantee of one encoding. PCM WAV is uncompressed, but a WAV can contain other formats and its source may already have been lossy.
Is M4A the same as AAC?
No. M4A commonly denotes MPEG-4 audio packaging; AAC is a lossy codec that can be stored in it. An M4A can instead contain another encoding such as Apple Lossless.
Can I convert MP3 to FLAC or WAV to improve quality?
Those formats can be useful for a later workflow, but conversion cannot recover information previously discarded by MP3 encoding. Start from a better original if available.
Can I change a file type by renaming the extension?
No. Renaming does not convert the audio or reliably change its packaging. Use a suitable converter when a different format is required.