Audio Converter (to MP3 or WAV)

An audio converter changes a sound file from one format to another, for example M4A to MP3 so an old player or upload form accepts it, or FLAC to WAV for editing software. Our free audio converter turns M4A, AAC, MP3, WAV, FLAC, OGG, Opus and WebM files into MP3 or WAV, right in your browser. Choose the bitrate, keep the original sample rate or set 44.1 kHz or 48 kHz, switch to mono, and optionally normalise the volume so quiet recordings are easier to hear. Convert up to 20 files at once and download them individually or as a ZIP. Nothing is uploaded.

How to use the Audio converter

1. 1 Add your audio filesDrop up to 20 files onto the tool or choose them from your device. Voice memos (M4A), podcasts (MP3), lossless music (FLAC, WAV) and web audio (OGG, Opus, WebM) all work in current browsers.
2. 2 Choose MP3 or WAVMP3 for small files that play anywhere; WAV for editing software, phone systems or anything that asks for uncompressed audio.
3. 3 Set quality and sample ratePick an MP3 bitrate, then keep the original sample rate or force 44.1 kHz (CD and music standard) or 48 kHz (video standard).
4. 4 Choose mono and normalisation if neededMono suits speech and halves WAV file sizes. Normalise volume raises quiet recordings so their loudest peak sits at −1 dB.
5. 5 Convert and downloadPress Convert, wait for the progress to finish, then preview or download each file, or download the batch as a ZIP.

Common audio formats explained

Audio formats fall into two groups. Lossy formats such as MP3, AAC (often in an M4A file), Ogg Vorbis and Opus throw away sounds you are unlikely to hear in order to make files much smaller. Lossless formats such as WAV and FLAC keep every sample exactly, so they sound identical to the original recording but take far more space.

• MP3: the most widely supported audio format. Plays on virtually every device, car stereo, website and podcast platform.
• M4A and AAC: the default for iPhone voice memos, Apple Music purchases and many Android recorders. Slightly more efficient than MP3 but not accepted by every system.
• WAV: uncompressed PCM audio. Large, simple and accepted by almost all editing software, phone systems and broadcast workflows.
• FLAC: lossless but compressed, typically around half the size of WAV. Popular for music archives but not supported by every player.
• OGG and Opus: open formats used by browsers, games, WhatsApp voice notes and web calls. Opus is excellent for speech at low bitrates.
• WebM audio: what browsers usually produce when you record sound on a website, typically containing Opus.

Popular conversions and when to use them

M4A to MP3 is the conversion people search for most. iPhone voice memos and many recorder apps save M4A, but some upload forms, older car stereos, website builders and hold-music systems only accept MP3. Converting at 128 kbps is plenty for speech; use 192 kbps or more for music.

WAV to MP3 is the usual way to shrink a recording before sharing it. A three-minute stereo WAV is about 30 MB; the same track as a 192 kbps MP3 is around 4 MB and sounds the same to most listeners. Keep the WAV as your master copy if you may need to edit it later.

FLAC to MP3 makes lossless music playable on devices that do not support FLAC, and saves space on phones. FLAC to WAV is useful when editing software or a DJ program refuses FLAC.

OGG, Opus or WebM to MP3 is handy for voice notes, browser recordings and game audio that other people cannot open. MP3 to WAV does not improve quality, but some phone systems, video editors and transcription services require WAV input.

Bitrate, sample rate and channels

Bitrate is how much data an MP3 uses for each second of sound. 128 kbps is a sensible minimum for most uses and comfortably good for speech. 192 kbps is a good default for music. 256 kbps and 320 kbps are the highest-quality options and worth using when files may be edited or played on good speakers.

Sample rate is how many times per second the sound is measured. 44.1 kHz is the CD and music standard; 48 kHz is the standard for video and broadcast. Choosing "Keep original" uses the file's own rate where the converter can read it from the file (WAV, FLAC, MP3 and Opus) and uses 44.1 kHz otherwise. MP3 cannot go above 48 kHz, so high-resolution files at 88.2 or 96 kHz are converted down to 48 kHz. Match the sample rate to the project you will use the audio in, for example 48 kHz for a video edit, to avoid another conversion later.

Channels decide between stereo and mono. Music normally benefits from stereo. Spoken recordings, phone calls and dictation usually sound the same in mono and the files are smaller. If the source file is already mono, choosing stereo simply keeps it mono rather than duplicating the channel.

What volume normalisation does

Recordings made on phones and laptops are often quieter than commercial audio, which makes them hard to hear on a phone speaker or in a car. The normalise option finds the loudest moment in each file and raises (or lowers) the whole file by the same amount so that peak lands at −1 dB, just below the point where digital audio starts to distort.

This is peak normalisation. It changes the overall level without altering the balance between quiet and loud parts, so it will not make whispered sections louder relative to shouting, and a single loud click or bang can limit how much a file is raised. It is different from loudness normalisation (measured in LUFS), which podcast and streaming platforms use to match perceived loudness between tracks. For a quick fix to a quiet voice memo or meeting recording, peak normalisation is usually all you need.

Quality: what converting can and cannot do

Converting never adds detail that the original file does not contain. Turning a 96 kbps M4A into a 320 kbps MP3 gives you a bigger file that sounds no better. Converting a lossy file to WAV preserves exactly what is there, which is useful for editing, but it does not undo the earlier compression.

Every lossy encode also discards a little more information. Converting MP3 to MP3 at a different bitrate, or going from AAC to MP3, loses some quality each time, which is why the tool reminds you when you re-encode MP3 files. Where possible, always convert from the best original you have, ideally a WAV or FLAC master.

Private conversion in your browser

Many online audio converters upload your files to their servers. This one decodes each file with your browser's built-in audio engine and encodes it on your own device, so recordings never leave it. That matters for voicemail, interviews, client calls, legal dictation and anything else that contains personal data, and it means there is no upload wait or server queue.

Because your device does the work, very long files need enough free memory to hold the decoded audio. A few hours of music in a batch is fine on most computers, while phones are happier with shorter files. Format support also depends on the browser: Safari, for example, has historically been less consistent with OGG files, so try Chrome, Edge or Firefox if one file will not open.

Examples you can copy

iPhone voice memo to MP3     MP3, 128 kbps, mono, normalise on
Music for a phone or car     MP3, 192-256 kbps, stereo, keep rate
Audio for a video edit       WAV, 48 kHz, stereo
Phone system or IVR prompt   WAV, mono (check the system's required rate)
Podcast draft to share       MP3, 128 kbps, mono

WAV 16-bit stereo 44.1 kHz   about 30 MB
FLAC                         about 15-20 MB
MP3 320 kbps                 about 7.2 MB
MP3 192 kbps                 about 4.3 MB
MP3 128 kbps                 about 2.9 MB

ffmpeg -i memo.m4a -c:a libmp3lame -b:a 192k memo.mp3

Common mistakes to avoid

Frequently asked questions