Audio Converter
Free audio converter: upload an audio file, choose an output format, and download the converted file.
What is an audio file converter and when do you need one
An audio file converter reads a source audio file, decodes its compressed or uncompressed data, and re-encodes the audio stream into a different container and codec. The output format determines which codec is used: MP3 uses a lossy perceptual encoder, WAV stores uncompressed PCM samples, and FLAC applies lossless compression that preserves every bit of the original signal.
You need one whenever a device, platform, or application refuses your current file format. A podcast host may require MP3, a video editor may expect WAV, and a streaming service may ingest only AAC or OGG. Converting lets you satisfy those requirements without re-recording.
Supported output formats
SimpleSize Convert Audio produces output in nine formats. Each serves a different purpose, so choosing the right one matters more than picking the tool.
- MP3 - Lossy compression with wide device support. Good for podcasts, music distribution, and any situation where file size matters more than perfect fidelity.
- WAV - Uncompressed PCM audio. No quality loss at all, but files are large. Preferred by audio editors and broadcast workflows.
- M4A / AAC - Lossy compression that achieves smaller files than MP3 at the same perceived quality. Common on Apple devices and YouTube.
- FLAC - Lossless compression. The file is smaller than WAV but the audio data is identical to the source. Preferred for archiving.
- OGG - Open-source lossy format used widely in games and web applications.
- WMA - Windows Media Audio, a Microsoft lossy format still required by some older Windows software.
- AIFF - Uncompressed PCM in Apple's container. Functionally similar to WAV, common in professional Mac audio workflows.
- MP2 - An older MPEG audio layer used in broadcast and video production pipelines.
How to convert an audio file with SimpleSize
The tool processes your file on the server and tracks progress in real time using a token generated in your browser. Here is the full flow.
- Go to simplesize.app/en/convert-audio or open the Converters section from the navigation bar.
- Drag your audio file onto the dropzone, or click it to browse your device. The file size limit is 100 MB.
- Select the output format from the list: MP3, WAV, M4A, AAC, FLAC, OGG, WMA, AIFF, or MP2.
- Optionally set a target bitrate between 32 and 320 kbps. If you leave it blank, the tool applies a sensible default. Note that WAV and FLAC ignore the bitrate setting because they are uncompressed or losslessly compressed.
- Click "Convert Audio". A progress bar shows percent complete and estimated time remaining. You can cancel the job at any point.
- When conversion finishes, click the download button to save the converted file.
No account or login is required. You get 10 successful conversions per IP address per day, with the counter resetting at midnight UTC.
Bitrate and quality: What the numbers mean
Bitrate controls how much data the encoder uses per second of audio. Higher bitrate means more data retained and therefore better fidelity, but a larger file. Lower bitrate means a smaller file with more compression artifacts, particularly in high-frequency content like cymbals or sibilant speech.
Common reference points for lossy formats like MP3 and AAC:
- 64 kbps - Acceptable for voice, podcasts, and audiobooks where bandwidth is tight.
- 128 kbps - The traditional web standard for music. Audible artifacts on critical listening, but fine for casual playback.
- 192 kbps - Transparent for most listeners on typical consumer headphones.
- 320 kbps - Near-transparent for even critical listeners. The maximum available here.
If you want to understand how bitrate affects file size across formats, the audio file size guide covers the math in detail.
Converting MP4 to MP3 and other video-source extractions
An MP4 file is a container that usually holds both a video track and an audio track. When you upload an MP4 here, the tool discards the video track and re-encodes only the audio stream into the format you choose. This is the standard approach for extracting a soundtrack, converting a recorded meeting to a podcast-ready MP3, or pulling music from a video download.
The same logic applies to other video containers: the audio track is decoded and re-encoded independently of any video data. If you need to reduce the size of the video file itself rather than extract audio, the MP4 compressor is the right tool for that job.
How this audio format converter compares to desktop software
Desktop converters run locally, which means no upload wait and no file size cap. They are the better choice for batch jobs of hundreds of files or for very large files above 100 MB.
A browser-based audio to audio converter like this one has different advantages:
- No installation or updates required.
- Works on any operating system including Chromebooks and mobile browsers.
- No configuration of codecs or libraries.
- The daily limit of 10 conversions covers most one-off needs without any commitment.
For occasional format changes, a web tool removes friction. For production pipelines or large batches, desktop software is more practical.
FAQ
You can upload any audio format the server can decode, including MP3, WAV, M4A, AAC, FLAC, OGG, WMA, AIFF, MP2, and audio tracks embedded in video containers like MP4. Output is available in MP3, WAV, M4A, AAC, FLAC, OGG, WMA, AIFF, and MP2. The decoder reads the source container and audio codec independently of the output you choose, so most common source formats are accepted without issue.
It depends on the output format. WAV and AIFF store uncompressed PCM samples, so no audio data is discarded. FLAC uses lossless compression, meaning the decoded output is bit-for-bit identical to the source signal. Lossy formats like MP3, AAC, OGG, and WMA discard audio data the encoder judges to be perceptually insignificant. Higher bitrate settings retain more of that data. Converting from one lossy format to another always introduces a second generation of loss, so use the highest practical bitrate when doing so.
WAV stores raw PCM samples with no compression at all. Every sample value is written directly to the file, which is why WAV files are large. FLAC applies a lossless compression algorithm: it finds redundant patterns in the PCM data and encodes them more efficiently, then reconstructs the original samples exactly on playback. Both formats preserve audio quality perfectly. FLAC files are typically 40 to 60 percent smaller than equivalent WAV files, making FLAC the better archival choice when storage matters.
An MP4 file is a container that typically holds a video stream and an audio stream as separate tracks. When you upload an MP4 and select MP3 as the output format, the server reads only the audio track, decodes it from its original codec (usually AAC), and re-encodes it using the MP3 encoder at your chosen bitrate. The video track is discarded entirely. The result is an MP3 file containing only the audio content of the original video.
Yes. The maximum upload size is 100 MB per file. If your file exceeds that, the server returns an error before processing begins. For reference, a 100 MB WAV file holds roughly 10 minutes of CD-quality stereo audio. A 100 MB MP3 at 128 kbps holds over an hour. Most podcast episodes, music tracks, and short recordings fall well within the limit.
The tool allows 10 successful audio conversions per IP address per day. The counter resets at midnight UTC. Failed conversions, cancelled jobs, and uploads that are rejected for errors do not count against the limit. Only a completed, downloadable conversion increments the counter. The audio daily limit is tracked separately from any video conversion limits on the site.
Files are processed on the server and made available for download via a temporary token generated in your browser. The token links your session to the output file. Files are not stored permanently and are not used for any purpose beyond delivering your download. No account is created and no login is required, so there is no persistent record tied to your identity. See the privacy policy for full details on data handling.
Bitrate is a property of lossy and variable-rate encoders that controls how much data is allocated per second of audio. WAV stores raw PCM samples at a fixed bit depth and sample rate, so there is no encoder to configure. FLAC uses lossless compression where the output size is determined by the content of the audio, not a target bitrate. For both formats, the bitrate field is accepted but ignored during processing.
The video converter re-encodes the video stream of a file and outputs a video container such as MP4, MKV, or WebM, preserving or re-encoding both audio and video tracks. This audio tool strips any video track entirely and outputs only an audio file. Use the video converter when you need to change video format or resolution. Use this tool when you only need the audio content in a different format or at a different bitrate.
Yes. While the progress bar is active, a cancel option is available. Clicking it sends a cancellation signal to the server, which marks the job as cancelled and stops the encoding process. A cancelled job does not count against your daily conversion limit. You can then upload a different file or adjust your settings and start a new conversion.
For voice recordings and podcasts, 64 to 96 kbps is usually sufficient because speech occupies a narrower frequency range than music. For music intended for casual listening, 128 kbps is a common baseline. For music where audio quality is important, 192 kbps is a reasonable choice that keeps file sizes manageable. At 320 kbps, most listeners cannot distinguish MP3 from the uncompressed source in controlled tests. The right choice depends on your playback context and storage constraints.
Yes. Because processing happens on the server rather than in the browser, the tool does not require significant device memory or CPU. You upload the file, the server handles the encoding, and you download the result. This means the tool works on smartphones and tablets running any modern browser, without installing an app. Upload speed from your mobile connection is the main variable that affects how long the transfer takes.