Trim audio

Fades stop the click

Cutting audio mid-waveform leaves an instant jump in level, which your ears hear as a click or thump. A fade of half a second at each end removes it. For a ringtone or a loop, one to two seconds sounds intentional rather than chopped.

Making a ringtone

Most phones want an M4A file of 30 seconds or less. Set your start and end, choose M4A, add a one second fade, and rename the result to .m4r if you are on iOS.

Why audio trimming is exact and video trimming is not

Cutting video accurately is awkward because a decoder can only start cleanly at a keyframe, which may be seconds away from where you asked. Audio has no such structure. Every frame stands close enough to alone that a cut can land where you put it, so the start and end times here are honoured to within a few milliseconds rather than snapped to the nearest convenient point. This is the one trimming job on the site you can trust to be precise.

The times are read as m:ss or h:mm:ss, and decimals work: 1:23.5 is a valid start. Leaving the end blank runs to the end of the file.

Choosing what to save as

If the source was already MP3 or M4A, saving back to the same format at the same bitrate is a second lossy encode. One hop is inaudible, so this is not worth agonising over, but it is worth knowing when you are about to trim the same file four times while deciding where the cut goes. Do the deciding, then do the trim once.

For anything that will be edited further, take WAV or FLAC: both are lossless, and you can compress at the end. For a ringtone or an alert take M4A, which is what phones expect. Opus is the best quality per byte of anything here and is the wrong answer if the file is going to somebody else's device, because support outside browsers is still patchy.

Fades, in practice

Half a second is enough to remove a click and short enough that nobody registers it as a fade. One to two seconds reads as intentional and is right for a ringtone, a loop or an excerpt that will be played on its own. Anything longer than three seconds on a thirty second clip is mostly fade.

A fade-out is positioned relative to the end of the trimmed audio, so it needs to know where the end is. If you leave the end time blank it uses the duration the browser reports, which is occasionally wrong on a variable-bitrate MP3 whose header is inaccurate. Typing an explicit end time removes the guesswork and lands the fade exactly.

Common questions

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