Audio Cutter

How to cut an audio file

1. Drop a file on the drop zone or click it to choose one. MP3, WAV, M4A/AAC, OGG, Opus and FLAC work in current browsers. The file is decoded on your device and its waveform appears.
2. Drag across the waveform to select a part. To adjust the selection, drag one of its orange edges. For exact times, type them in Start (s) and End (s); the arrow keys in those boxes move by a hundredth of a second.
3. Choose What to do with the selection: Keep the selection (trim) to keep only that part, or Delete the selection (keep the rest) to cut it out and join what is before and after it.
4. Optionally set a Fade in (s) and a Fade out (s) for the beginning and end of the result.
5. Press Play the result to hear exactly what will be exported, fades included. The playhead moves on the waveform.
6. Pick a Format (MP3 or WAV) and, for MP3, an MP3 bitrate, then press Export. Listen to the result in the player, then press Download.

Select all resets the selection to the whole file. The stats show the File length, the Selection and the Result length.

What happens to your file

Everything runs in your browser. The file is decoded with the Web Audio API into uncompressed samples, the part you choose is copied, and the result is encoded again: to 16-bit PCM WAV directly, or to MP3 with the LAME encoder (the lamejs port, loaded only when you export an MP3). Nothing is uploaded, so even long or private recordings stay on your device.

When you delete a selection, the two sides are joined with 5-millisecond micro-fades. Without them, the jump between two unrelated samples would produce an audible click at the splice.

Choosing a format

• MP3 plays everywhere: phones, cars, messaging apps, ringtone settings. 192 kbps is transparent for most music; 128 kbps is fine for speech and makes smaller files; 320 kbps is the maximum.
• WAV (16-bit PCM) is uncompressed: CD-quality, about 10 MB per minute in stereo at 44.1 kHz. Choose it when you will edit the file again, so you don’t stack two rounds of lossy compression.

Cutting an MP3 and exporting to MP3 re-encodes it. At 192 kbps or more, the loss is inaudible for normal listening. Export WAV if you need a perfect intermediate copy.

Tips

• To make a ringtone, keep 20 to 30 seconds and add a short fade out (1–2 s) so it doesn’t stop abruptly.
• To remove a cough or a silence from a voice recording, select it and choose Delete the selection (keep the rest).
• For precise edits on a long file, first make a rough selection with the mouse, then fine-tune the times in the boxes while listening.
• Fades are limited to half the result length, so a fade in and a fade out never overlap.