🔄 Convert Audio (MP3 / WAV)
Upload an audio file and convert it to MP3 or WAV — decoded and re-encoded entirely on your device, nothing uploaded anywhere.
About Convert Audio (MP3 / WAV)
This tool converts an audio file you already have into MP3 or WAV format. It's useful when an app or device only accepts one format — some voice recorders and answering-machine exports only produce WAV, some older players and car stereos only read MP3 — or when you specifically want WAV's lossless quality for further editing versus MP3's smaller file size for sharing or archiving.
Conversion works in two steps, both running in your browser via the Web Audio API. First, your file is decoded into raw PCM audio samples using decodeAudioData, which handles most common formats (MP3, WAV, OGG, M4A/AAC, and FLAC in browsers that support it). Then those samples are either written directly into a WAV file with a standard 44-byte header — a fast, lossless, purely mathematical operation — or re-encoded into MP3 using lamejs, a pure-JavaScript port of the LAME encoder that runs the actual MP3 compression algorithm entirely on your device.
MP3 encoding is CPU-bound JavaScript work, so a long file (say, a 45-minute podcast) takes noticeably longer to convert than a 3-minute song, and higher bitrates take a bit longer than lower ones. WAV conversion is essentially instant regardless of length, since it's just repackaging the same samples rather than compressing them.
Frequently asked questions
Which audio formats can I upload?
Anything your browser can decode — MP3, WAV, OGG, M4A/AAC, and FLAC in browsers that support it. If a file fails to load, try re-exporting it in a more common format first.
Is MP3 or WAV better?
WAV is uncompressed and lossless, so it's larger but has zero quality loss — good for further editing. MP3 is compressed and much smaller, which is better for sharing, streaming, or saving storage, at a small, usually inaudible quality cost.
Why does converting to MP3 take longer than WAV?
WAV output just repackages the decoded audio samples with a file header — no compression happens. MP3 output runs a real encoding algorithm (via the lamejs library) on every sample, which is genuine CPU work done in JavaScript.
Is there a file size or length limit?
No hard limit is enforced, but very long files use more memory and take longer to encode, since everything happens in your browser rather than on a server. A typical song or short recording converts in a few seconds.
Is my audio file uploaded anywhere?
No — decoding and encoding both happen locally using the Web Audio API and the lamejs JavaScript encoder. The file never leaves your device.