An MP3 converter turns any audio file into the format every device can play. This free browser-based tool accepts WAV, OGG, M4A, AAC, FLAC, and Opus, converts to MP3 at 128, 192, 256, or 320 kbps, and handles several files in one batch. Everything runs on your device, so nothing is uploaded and no account is required.
Audio Converter changes audio files between the three formats that cover nearly every everyday use: MP3 for compatibility, WAV for uncompressed editing, and OGG for open format playback. Drop in one file or a whole batch, choose the output format and bitrate, and download the results. Input can be MP3, WAV, OGG, M4A, AAC, FLAC, Opus, or the audio inside a WebM file, so it also works as a way out of the formats that voice recorders and messaging apps produce. Files are converted one at a time and each one reports its own status, so a single unreadable file marks itself as failed instead of stopping the whole batch. All of it runs in your browser through a WebAssembly build of FFmpeg, meaning your audio is never uploaded and nothing is stored on a server. The first conversion downloads the encoder, roughly 32MB, which your browser then caches. For video files, Video Compressor reduces file size using the same engine, and for grabbing artwork rather than audio, YouTube Thumbnail Downloader pulls preview images from any YouTube video.
The split that matters most in audio formats is lossy against lossless. A lossless format such as WAV or FLAC stores enough information to reconstruct the original waveform exactly, which is why WAV files run around 10MB per minute of stereo CD quality audio. Lossy formats such as MP3, OGG Vorbis, AAC, and Opus use psychoacoustic models to discard sound that listeners are unlikely to perceive, typically hitting a tenth of the size for audio most people cannot distinguish in normal listening. The important consequence is that the discarded information is gone permanently. Converting MP3 to WAV inflates the file back to full size without recovering anything, and each further lossy conversion compounds the loss, an effect known as generation loss. The practical rule is to keep a lossless master and export lossy copies from it, rather than converting between lossy formats repeatedly. Bitrate is where quality and size are actually traded. At 128 kbps most listeners cannot reliably distinguish MP3 from the source on laptop speakers or earbuds, though the gap becomes audible on good headphones with dense music. At 256 to 320 kbps MP3 is effectively transparent for nearly everyone. OGG Vorbis reaches similar quality at a somewhat lower bitrate, because it is a newer design than MP3, and Opus does better still, which is why messaging apps and voice chat use it. Sample rate and bit depth apply to the uncompressed side. This tool writes WAV at 16 bit and 44.1 kHz, the CD standard, which is the format editing software and mastering workflows expect, and which every audio application on every platform can open without conversion.