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Lossless Audio Formats: Differences Between WAV, FLAC, MP3 and AAC

What uncompressed, lossless and lossy really mean, how much space each format needs, and which one to use for recording, editing, podcasts and streaming.

By Yunus S. Published Updated

WAV stores audio uncompressed, FLAC compresses it without losing anything, and MP3 and AAC make files far smaller by removing detail that is hard to hear. Record and edit in WAV, archive in FLAC if you need to save space, and publish in MP3 or AAC. Converting a lossy file back to WAV does not restore what was removed.

In Short

The short version:

  • WAV: uncompressed, about 10 MB per minute at CD quality. For recording and editing.
  • FLAC: lossless compression, roughly half the size of WAV. For archiving and lossless listening.
  • MP3: lossy, about 1 to 2.5 MB per minute. Plays everywhere.
  • AAC: lossy, more efficient than MP3. Standard on Apple devices and streaming services.
  • Convert from lossless to lossy only once, at the end.

Audio Format Comparison: WAV vs. FLAC vs. MP3 vs. AAC

Format Type Size per minute (stereo) Best for
WAV (.wav) Uncompressed About 10 MB at 16-bit/44.1 kHz Recording, editing, mixing, mastering
FLAC (.flac) Lossless compression About 5 to 7 MB Archiving, lossless music libraries
MP3 (.mp3) Lossy compression About 1 MB at 128 kbps, 2.4 MB at 320 kbps Podcasts, sharing, maximum compatibility
AAC (.aac, .m4a) Lossy compression About 1 to 2 MB Streaming, phones, Apple devices

Uncompressed, Lossless and Lossy: What the Words Mean

Three terms describe how a format treats the recorded audio. Uncompressed means every sample is written out in full. Lossless means the data is packed more tightly, like a ZIP file, and unpacks to exactly the same samples. Lossy means some of the audio is permanently discarded to make the file much smaller. Uncompressed and lossless files sound identical; the only difference between them is size.

High-fidelity studio headphones on a desk
Uncompressed and lossless formats keep everything that was recorded; lossy formats keep what you are likely to hear.

What Is a WAV File?

WAV (Waveform Audio File Format) was introduced by Microsoft and IBM in 1991 and is the standard format for audio production. A WAV file normally contains PCM audio: the sound wave measured tens of thousands of times per second and written down as plain numbers, with nothing left out.

The price is size. One minute of stereo audio at CD quality (16-bit, 44.1 kHz) takes about 10 MB; at 24-bit and 48 kHz it is about 17 MB. In return, a WAV can be opened, edited and saved as often as you like without losing anything, which is why it is the right format for recording and for every step of editing.

What Is FLAC?

FLAC stands for Free Lossless Audio Codec. It compresses audio the way a ZIP file compresses a document: the file gets smaller, typically 40 to 60 percent smaller than the WAV, and when it is played, exactly the original samples come back.

FLAC is a good choice for archiving finished masters and for music libraries where you want full quality without the size of WAV. It also stores titles, artists and cover art, which WAV handles poorly. Its limits are practical: not every editing program or older device opens FLAC. Tools such as the Audio Trimmer and the Sound Optimizer open FLAC files directly.

MP3 and AAC: How Lossy Compression Works

MP3 and AAC make files five to ten times smaller than WAV by removing sound that listeners are unlikely to notice. They rely on psychoacoustics, the study of how we hear: a loud sound makes quieter sounds at nearby frequencies inaudible, so the encoder spends its data on what can be heard and discards the rest. Karlheinz Brandenburg, one of the developers of MP3 at Fraunhofer IIS, describes the method in MP3 and AAC Explained .

How much is removed depends on the bitrate, the amount of data per second. At 128 kbps an MP3 is small and fine for speech, but music can lose some sparkle; at 192 kbps and above, most people cannot tell it from the original in normal listening. What matters for your workflow is that the loss is permanent and adds up: every time a lossy file is edited and saved as a lossy file again, a little more is removed.

What Is AAC?

AAC (Advanced Audio Coding) was developed as the successor to MP3. At the same bitrate it generally preserves more of the original, especially at lower bitrates. It is the standard format on Apple devices and is used by most streaming and video platforms; its files usually end in .m4a or .aac. MP3 remains the format that every device and program understands.

Person listening to a podcast on a phone with earphones
For listeners, a small file that loads quickly matters more than detail they cannot hear.

The Best Audio Format for Each Job

Task Format Why
Recording WAV, 24-bit Nothing is lost, and there is room for later processing
Editing and mixing WAV Can be saved again and again without loss
Archiving a finished master WAV or FLAC Full quality; FLAC takes about half the space
Podcast episode MP3, 128 to 192 kbps Accepted by every podcast host and app; small downloads
Music for a distributor (Spotify, Apple Music) WAV or FLAC The platform creates its own streaming files from your master
Sending a file by email or messenger MP3 or AAC Small enough to send, and it plays on any phone

The rule behind the table: stay lossless for as long as you are working on the audio, and convert to a lossy format once, as the very last step. For loudness targets, see How to Normalize Audio Without Clipping; for music releases, How to Master Audio for Spotify.

How to Convert Between Formats

All of these run in your browser, so your files are not uploaded. You can choose the MP3 bitrate or the WAV bit depth and convert several files at once.

Audio editing software showing a waveform on a computer screen
Work in WAV, publish in MP3 or AAC: convert once, at the end.

Three Things Conversion Cannot Do

  • It cannot restore quality. An MP3 converted to WAV or FLAC is still the MP3, in a bigger file.
  • A higher bitrate does not add detail. Converting a 128 kbps MP3 to 320 kbps only makes the file larger.
  • Lossy to lossy costs quality. Converting MP3 to AAC, or AAC to MP3, compresses the audio a second time. Go back to the lossless original whenever you can.

Convert a File Now

Turn a WAV into an MP3 at the bitrate you choose, without uploading it.

Open the WAV to MP3 Converter

Free, no sign-up, and your files never leave your device.

Frequently Asked Questions

Does converting an MP3 file to WAV improve audio quality?
No. The detail that was removed when the MP3 was created cannot be restored. The WAV contains exactly the same sound in a much larger file. Converting is still useful when an editing program or device requires WAV.

What audio format do Spotify and other distributors want?
Music distributors ask for a lossless master, usually WAV or FLAC at 16-bit or 24-bit. The streaming platform then creates its own files from it, for example Ogg Vorbis and AAC on Spotify.

What is the best audio format for podcasts?
Record and edit in WAV, then publish an MP3. MP3 is accepted by every podcast host and app; 128 kbps is common for speech and 192 kbps for episodes with a lot of music.

Why are WAV files so much larger than MP3 files?
A WAV stores every sample of the audio in full, about 10 MB per minute at CD quality. An MP3 removes sound that listeners are unlikely to notice and stores the rest very efficiently, which makes it five to ten times smaller.

What is the difference between FLAC and WAV?
Both contain exactly the same audio. WAV stores it uncompressed; FLAC compresses it without loss, so the file is roughly half the size and can carry titles and cover art. WAV is supported by more editing programs and devices.

Is AAC better than MP3?
At the same bitrate, AAC generally sounds a little better, especially at low bitrates. MP3 is supported by more old devices and programs. For modern phones, computers and streaming, AAC is the more efficient format.

What is an M4A file?
An M4A file is an MP4 container that holds only audio, usually AAC. Phones use it for voice memos, and music stores use it for songs. It can be converted to MP3 or WAV like any other audio file.