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Make an audio file smaller so it fits an email, a messaging app or an upload limit. It is re-encoded at a lower bitrate in your browser, so the recording is never uploaded.
Your media is processed in your browser and is not uploaded to our servers for conversion. Page assets (including the converter engine) still load over the network.
Select or drop a video or audio file
MP4, MOV, WebM, MKV, M4A, WAV, FLAC, OGG and more. Converted on your device.
Click, tap, or drop a fileChoose the recording
Drop or select an MP3, WAV, M4A, FLAC or any other audio or video file.
Check the size estimate
Small (64 kbps) is preselected. The page shows the expected file size before you convert.
Adjust if needed
Pick M4A for better quality at the same size, or 128 kbps if it's music and the file can be a bit larger.
Compress and download
The file is re-encoded on your device. Download it when it's ready.
The size of compressed audio depends only on its bitrate and length: at 64 kbps an hour takes about 28 MB, so a 25 MB email limit fits about 50 minutes, and a 10-minute voice recording becomes under 5 MB. A 320 kbps MP3 shrinks about 5 times, a WAV about 20 times.
If your file is already 64 kbps or lower, re-encoding it won't make it meaningfully smaller and will cost quality. In that case, shorten it with the Audio Cutter instead.
Audio can't be zipped much smaller, so the tool re-encodes it at a lower bitrate with FFmpeg in WebAssembly: MP3 through the LAME encoder or M4A through AAC. At 64 kbps, speech stays perfectly clear; music keeps its tune but loses some sparkle in the high frequencies.
AAC (M4A) sounds noticeably better than MP3 at low bitrates. Choose M4A unless the file must be MP3 for an old player or an upload form.
See the expected size before you convert, so you know it will fit.
Lectures, podcasts, voice notes and meetings stay clear at 64 kbps.
MP3, WAV, M4A, FLAC, OGG, AMR, or the soundtrack of a video.
Recordings are compressed on your device, never uploaded.
No. The conversion runs in your browser with a WebAssembly build of FFmpeg. Your file is read from your device and the result is saved back to it; nothing is sent to our servers.
At 64 kbps, audio takes about 28 MB per hour, so recordings up to about 50 minutes fit. For longer recordings, cut them into parts with the Audio Cutter.
It was probably already compressed at a low bitrate. Re-encoding a 64 kbps file at 64 kbps can't shrink it. Shorten it instead, or check the size estimate before converting.
Speech sounds fine at 64 kbps. Music is listenable but loses some detail; use 128 kbps (Standard) for music you care about.
M4A sounds better at the same small size. MP3 is only better when an old device or a form specifically requires MP3.
Files up to 4 GB and 4 hours long on a computer, or 2 GB and 2 hours on a phone. The video is read in pieces rather than loaded into memory, so large recordings work; only the audio file being written has to fit in memory.
Related: Audio Cutter · WAV to MP3 · Compress Video to Size · Audio Converter · All tools