Audio Compressor

Compressing audio here means re-encoding a recording at a lower bitrate, so the file carries less data for every second of sound — an MP3 is as large as its bitrate times its length. Lowering the sample rate or switching to mono changes the sound (fewer high frequencies, one channel instead of two) but not the size of the MP3. The tool decodes your source with the audio decoder built into your browser, applies the settings you choose, and writes the result as MP3 with an encoder that runs inside the page.

You can start from one of four presets — High Quality, Medium Quality, Small Size, or Minimum Size — or open Custom Settings and set the bitrate, sample rate, and mono or stereo yourself. An optional Normalize step raises the loudest peak to just below full volume before encoding; it scales the whole recording by one amount, so quiet and loud parts keep their balance.

It earns its place when a file is too heavy for where it needs to go: an email attachment, a chat app with an upload limit, or a podcast host that bills by storage. Spoken-word content — interviews, lectures, voice memos — is the easiest win, because speech stays clear at bitrates well below what music needs.

The Minimum Size preset is tuned for exactly that, trading away fidelity you won't notice in speech for a much smaller result. For music you still want to enjoy, High Quality at 192 kbps holds up well while cutting size. When the recording is still inside a video file, pull the track out with the video to audio converter first; and a two-hour session that is too long to send in one piece can be cut up with the video splitter before each part is extracted and compressed.

Say you have a 60 MB stereo WAV of a recorded talk, roughly six minutes long. At 96 kbps an MP3 takes about 0.7 MB per minute, so the result comes out around 4 MB. Choosing mono would not change that number: an MP3's size depends only on its bitrate and its length. The estimate under the settings shows the size before you start, so you can aim at a target — under 10 MB, say — and see whether the bitrate you chose reaches it without processing the whole file first.

You can load MP3, WAV, OGG, AAC, M4A, FLAC, or WebM files up to 500 MB, and the output is always MP3. Lower bitrates shrink the file but discard more detail, so the trade-off becomes audible past a point — 64–96 kbps suits voice, while 128–192 kbps keeps music pleasant. An MP3 can't get smaller than its own bitrate allows: if the original is already at or below the bitrate you pick, the result isn't smaller and the tool says so, suggesting a lower preset when one would help.

Because everything runs on your own machine, very long or high-resolution files can exhaust the browser's memory; when that happens, a shorter clip or a smaller source usually processes cleanly. A file with an unusual or unsupported codec may fail to decode, in which case running it through the audio converter into a common format like WAV first tends to fix it.