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Audio tools
Audio · Free · Private

Audio Converter

Drop in songs, voice notes or videos and get the format you need, with the size before and after for every file.

  • Runs in your browser
  • No upload
  • No sign-up

Drop files here, or

MP3, WAV, M4A, AAC, OGG, Opus, FLAC, AIFF, or a video · up to 50 at once

Stays on your device

    About this tool

    Audio Converter changes a recording from one format to another. Turn a huge WAV into an MP3 that fits in an email, make a FLAC copy without losing a single sample, or save just the sound from a video as an MP3.

    It reads MP3, WAV, M4A, AAC, OGG, Opus, FLAC and WebM audio, and the sound inside MP4, MOV, WebM and MKV videos. It writes MP3, M4A (AAC), OGG, WAV at 16 or 24 bits or 32-bit float, and FLAC at 16 or 24 bits. Change the sample rate to anything from 8 kHz for a phone system to 48 kHz for video: the resampler is a proper band-limited filter, so nothing folds back as a whistle. Tick “Normalise on convert” and every file comes out equally loud, measured to the BS.1770 standard.

    All of it happens in your browser. Your files are not uploaded to AroraTools or anyone else, there is no sign-up and no watermark, and you can convert a whole album, up to 50 files, in one go and save the lot as a single ZIP.

    How to use Audio Converter

    1. Press “Choose files” or drag audio or video files onto the box. Each one appears with its length, format, sample rate and file size.
    2. Under “Convert to”, pick MP3, M4A (AAC), OGG, WAV or FLAC. A greyed-out choice means this browser can’t write that format; the note below explains why.
    3. For MP3, M4A and OGG, choose a quality. 192 kbps is a good default for music; 128 kbps is fine for speech and podcasts.
    4. Optional: tick “Normalise on convert” and pick a loudness, or open “More options” for the sample rate, channels, bit depth and whether to keep the title and cover art.
    5. Press “Convert”. Each row shows its progress, then the new format, its size and how it compares with the original. Tap a finished row to listen to it, download files one by one, or download them all together as a ZIP.
    Example

    A 3-minute WAV from a recorder (30.3 MB) becomes a 4.1 MB MP3 at 192 kbps, about 86% smaller. As FLAC it is typically around half the WAV’s size and plays back identically.

    Features

    • Writes MP3 (64 to 320 kbps), M4A (AAC), OGG (Opus or Vorbis), WAV (16-bit, 24-bit or 32-bit float) and FLAC (16 or 24-bit).
    • Sample rates of 8, 16, 22.05, 32, 44.1 and 48 kHz, converted with a windowed-sinc filter rather than straight-line guessing.
    • Normalise on convert: −14 LUFS (Spotify, YouTube), −16 LUFS (Apple Music, podcasts), −23 LUFS (broadcast) or a −1 dBFS peak. Loudness targets never push the true peak past −1 dBTP.
    • Title, artist, album and cover art are carried over, or left out if you untick the box.
    • Reads MP3, WAV, M4A, AAC, OGG, Opus, FLAC and WebM, plus the sound of MP4, MOV, WebM and MKV videos.
    • Batch conversion of up to 50 files, with the size before and after and a single ZIP download.
    • Listen to any converted file on the page before you download it.

    Tips and good to know

    • Converting MP3 to M4A (or any lossy format to another) can’t bring back lost detail. Start from the best copy you have.
    • For speech or a phone line, 16 kHz mono is plenty; for music keep 44.1 or 48 kHz.
    • FLAC is the one to keep for archiving: about half the size of WAV and exactly the same samples. Choose 24-bit only if the original is 24-bit.
    • M4A is made at 44.1 or 48 kHz, and Opus always plays at 48 kHz, so lower rates there use the nearest one; the result says so.
    • When 16-bit WAV or FLAC is resampled or normalised, a faint dither is added so the rounding doesn’t turn quiet fades gritty.
    Are my audio files uploaded anywhere?

    No. The converting is done by your browser on your own device. Your files are never sent to AroraTools or to anyone else.

    Is it free? Are there limits?

    It is free, with no sign-up and no watermark. You can convert up to 50 files per batch. The only real limit is your device’s memory, which matters for very long recordings saved as WAV.

    Does it work on iPhone, Android and offline?

    Yes, in an up-to-date Safari, Chrome, Firefox or Edge. Which formats you can create depends on the browser, and the page tells you. You need the internet to open the page and, the first time you save an MP3, to load the MP3 encoder; the converting itself happens on your device.

    Why is M4A or OGG greyed out?

    Your browser has no encoder for that format. Firefox, for example, has no AAC encoder, so it can’t make M4A files. The note under the format choices says exactly what is missing. MP3, WAV and FLAC work everywhere.

    Can I convert a video to MP3?

    Yes. Add an MP4, MOV, WebM or MKV video and choose MP3. Only the sound is kept, and the picture is dropped.

    Does converting to FLAC improve the quality?

    No. FLAC keeps exactly what you give it. If the original is an MP3, the FLAC sounds exactly like that MP3, just in a bigger file. FLAC is best for converting from WAV, or for archiving.

    What does “Normalise on convert” do?

    Each file is read once to measure its loudness, then turned up or down by one fixed amount as it is converted, so a mixed batch plays back at an even level. Nothing is squashed: if reaching the target would push peaks past −1 dBTP, the file is left a little quieter instead.

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