How to fade audio in and out
- Drop your audio file into the box or choose it. Several files at once work too, and they all get the same fades.
- Enter the Fade in (s) and Fade out (s) lengths in seconds. Use 0 to skip one, and decimals such as 0.5 work too.
- Skip to the end of the Result player to hear the fade-out, then download.
Where fades help
- Ending a song early: after you trim an MP3 in the middle of a verse, a 4 or 5 second fade-out makes the cut sound intentional.
- Background music for videos and slideshows: a fade-in and fade-out keep the music from starting or stopping abruptly.
- Podcast intros: fade the theme music out over a couple of seconds before the first voice comes in.
- Alarms and ringtones: a slow fade-in so the sound doesn’t start at full volume.
- Clicks at edit points: a cut that lands mid-wave makes an audible click. A fade of 0.05 seconds on that side removes it without being heard as a fade.
To stitch several clips into one file first, use join audio, then fade the result.
The fade curve
The volume follows an equal-power curve, a quarter of a sine wave, rather than a straight line. Compared with a straight line it stays fuller for longer and then drops away faster close to silence. It’s the curve audio editors commonly use for crossfades, because two of them overlapping keep the total level steady.
In practice this means the last moment of a fade-out falls off fairly quickly. If an ending seems to vanish too suddenly, make the fade longer rather than starting it later. The audio is processed in your browser, so nothing is uploaded.