Trim audio

How to Trim the audio

1. 1

   Add your audio file

   MP3, WAV, FLAC, M4A, AAC, OGG or Opus, up to 200 MB. The waveform appears before you decide anything.

2. 2

   Drag the marks on the waveform

   Or type exact timecodes. Keeping the selection and removing it are one setting apart.

3. 3

   Click Trim and download

   The cut is accurate to a single sample — about 23 microseconds at CD quality.

Why there is a waveform and not just two boxes

Audio has no picture. Asked to cut from 1:04.20 to 1:31.75, nobody can tell whether those numbers land on the start of a word or halfway through it. The only way to know is to see where the sound is. The waveform here is drawn from the file itself as soon as you add it, before you have decided anything, and it shows exactly what you would expect: loud passages as tall blocks, silence as a thin line, the gaps between sentences as visible notches. Dragging a mark to a notch is a completely different operation from guessing a number, and it is the reason this page has a waveform rather than a form.

Cut to the sample, not to the frame

This page decodes the audio and cuts the sample array directly, which means the marks land exactly where you put them; the precision is one sample, about 23 microseconds at 44.1 kHz. Tools that cut compressed audio without decoding it are bound by frame boundaries instead: an MP3 frame is about 26 milliseconds long and an AAC frame about 23, so the cut moves to the nearest boundary and the marks drift by up to that much. That is inaudible on a music fade and very audible when you were trying to cut exactly before a word.

Removing the middle instead of keeping it

The same two marks do both jobs. Keeping the selection is the obvious one. Removing it, to cut out a cough, a phone ringing or thirty seconds of dead air at the start of a recording, takes everything outside the marks and joins the two halves. Because the join happens on sample boundaries there is no gap and no overlap, and the result is exactly as long as the original minus what you removed.

The click at the cut, and how to get rid of it

Cutting at an arbitrary point almost always lands mid-waveform, where the signal is not at zero. Playback then jumps from that value straight to silence, and a jump is a click: audible, unmistakable, and the single most common complaint about every trimming tool ever made. Turning on soft edges applies a 30-millisecond fade at each end of the result, which is far too short to hear as a fade and long enough to remove the discontinuity entirely. It costs nothing and is worth turning on for anything that will be listened to rather than processed further.

No engine to download

The result is written as WAV, which the browser can produce on its own: decoding is native through the Web Audio API and writing a WAV is a 44-byte header. The 8 MB audio engine that most tools on the web download before they can start is never requested here, so the page works on the first visit and keeps working offline.

Frequently asked questions