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A fade is the difference between a track that ends and one that just stops. Set the length, choose a curve that suits the material and watch the fade drawn over the waveform, or blend two files into one with a crossfade.
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Overview
Technically, a fade is a gain envelope multiplied against the audio. A linear fade lowers the amplitude in equal steps, but hearing is roughly logarithmic, so a linear fade out seems to hang near full volume and then collapse at the very end. The exponential curve here falls evenly in decibels (from 0 to −60 dB), which most listeners hear as a smooth, natural fade out. The logarithmic curve is its mirror image: it changes quickly first and gently at the end. The S-curve eases in and out at both ends and is a good default for fade ins.
Fade in and fade out are set independently, each up to 60 seconds and each with its own curve. The shaded overlay on the waveform shows how much each part is turned down, and the Hear the fade out button jumps to just before the fade so you don’t have to listen to the whole song. The preview uses Web Audio gain automation with the same envelope as the export, which is rendered with an OfflineAudioContext, so they sound identical.
The Crossfade two files mode blends the end of track A into the start of track B. B begins before A finishes, and over the overlap (up to 30 seconds, and at most half of either track) A fades out while B fades in. With a linear crossfade both tracks are at half amplitude in the middle, which sums to about 3 dB less power, so the overlap sounds like a dip. Equal power, the default here, follows a sine and cosine pair whose powers always add to one, keeping loudness steady. Markers show where B comes in and A ends, and Play the transition starts three seconds before the overlap.
Fade length depends on context. Radio edits of pop songs often fade over 5–10 seconds, podcast music beds over 2–4 seconds, and a cut in the middle of speech needs only 10–50 milliseconds to remove a click. Exports can be MP3, M4A, WAV, FLAC, OGG or Opus.
| Curve | Shape | Good for |
|---|---|---|
| Linear | Straight line in amplitude | Very short fades, de-clicking |
| Exponential | Even steps in decibels | Music fade outs |
| Logarithmic | Fast at first, then gentle | Quick fade ins on loud starts |
| S-curve | Eased at both ends | Fade ins, smooth transitions |
| Equal power | Sine/cosine pair | Crossfades between songs |
Choose Fade in / out or Crossfade two files at the top.
For fades, open a file, set each fade’s length and pick a curve for each.
For a crossfade, add track A and track B, then set the overlap and curve.
Preview, or jump straight to the fade out or the transition.
Pick an output format and download the result.
Use cases
When a track runs longer than your video, a 6–8 second exponential fade out lets the music end naturally instead of being cut off.
Fade intro music in over a couple of seconds with an S-curve and out under the host’s first words, the way radio shows handle their theme tunes.
Crossfade two songs over a few bars with the equal-power curve so the energy carries from one into the next without a gap or a dip.
A short fade in removes the thump of a recorder starting, and a fade out hides the clunk of the stop button at the end of a voice memo.
Pro tips
Answers to common questions about the fade / crossfade.
Loudness perception is roughly logarithmic. Halving the amplitude lowers the level by only about 6 dB, which still sounds fairly loud, so most of a linear fade seems to change little and the last second does all the work. The exponential curve spreads the change evenly in decibels.
The outgoing track follows a cosine curve and the incoming one a sine curve. Their combined power stays constant through the overlap, so there is no dip in volume in the middle of the transition.
It can be up to 30 seconds, but never more than half of either track, so both tracks still have a part that plays on its own.
Yes, the fade is applied to the decoded audio, so the result is encoded again. WAV or FLAC output avoids any further quality loss; MP3, M4A, OGG and Opus re-encode once at the bitrate you choose.
No. ToolEnhancer processes files on your own device inside the browser. They are never sent to, stored on or seen by our servers.
Yes. The fade / crossfade is free to use with no sign-up, no watermarks and no daily limits.