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Audio fade in and fade out.
Fade it over eight bars, not eight seconds.
Add a fade in or a fade out to any file, on a curve that sounds even rather than one that looks even on a graph. The tempo is read off the track so you can set the length in bars, which is the only unit a fade actually makes sense in. Lossless out, nothing uploaded.
Drop tracks to fade
WAV, AIFF, FLAC, MP3 or M4A. Drop a whole folder’s worth — one set of settings is applied to all of them and they come back as a single archive. Nothing is uploaded; the page makes no network request.
The curve nobody explains
Why a linear fade sounds broken.
It is the default in almost every editor and it is the wrong shape for a fade you want to be invisible.
Halfway through a linear fade the signal is at 50% amplitude. That sounds like a drop of about 6 dB, which is only a quarter of the way down in perceptual terms — so the first half of the fade barely does anything and the second half has to do all the work. The result is a fade that hangs and then falls away, and it is the reason so many home-made outros sound like somebody pulled a fader too fast at the end.
An equal-power curve puts the halfway point at about 70% amplitude, which is roughly 3 dB down and genuinely half way to the ear. Two of them crossed over add up to constant power throughout, which is why every mixer crossfader and every DAW crossfade uses this shape — it is the only curve where a blend does not dip in the middle.
The other three are here because they are the right answer to specific problems rather than as decoration. Exponential holds its level and then drops fast, which is what you want going into a hard cut. Logarithmic drops immediately and then trails, which is how you duck a track under a voice. An S-curve is slow at both ends, which protects the first and last moments of a fade when something important happens there. Linear is still on the list, because sometimes you genuinely want a mathematically straight ramp — you should just know what you are choosing.
The default curve everywhere else is the wrong one
A linear fade ramps amplitude in a straight line, which sounds nothing like an even fade. Perceived loudness tracks power rather than amplitude, so a straight amplitude ramp holds near full volume for most of its length and then collapses at the end — you have heard it a hundred times as a fade that seems to do nothing and then suddenly vanishes. An equal-power curve, which is a quarter of a sine wave, is what a mixer's crossfader does and what your ear is expecting. It is the default here and the other four are for jobs where you want something specific.
Bars, because seconds are meaningless on a record
Nobody has ever wanted a 7.4-second fade. What they wanted was for the fade to cover the last 16 bars, and 7.4 seconds is what that happens to be at this tempo. So the tempo is detected on drop and the length buttons are in bars — 4, 8, 16, 32 — with the seconds shown next to them. A fade that starts on a phrase boundary and ends on one is invisible; a fade that starts three beats into a phrase is something a listener notices without being able to say why.
You can see where it lands before you commit
The track is drawn as a frequency-split waveform the moment you drop it, and the fade regions are shaded over the top as you change them. So you can see that your 16-bar outro fade actually starts at the beginning of the outro rather than halfway through the last drop, which is the entire reason to look at a waveform. Change the length and the shading moves; nothing is written to a file until you ask for it.
Five curves
Which shape for which job
The choice is about what happens at the ends of the fade, not about taste.
| Curve | What it does | Reach for it when |
|---|---|---|
| Equal power | A quarter-sine. Halfway through the fade you are about 3 dB down, which is halfway to the ear. | Almost always. This is what a crossfader does and what an invisible fade needs. If you are not sure, this one. |
| Linear | A straight amplitude ramp. Halfway through you are 6 dB down. | You want a mathematically straight ramp for a reason you can name, or you are matching a fade somebody else already made. |
| S-curve | Gentle at both ends, quick through the middle. | Something important happens at the very start or the very end of the fade and you want it to hold before the level moves. |
| Exponential | Stays loud, then falls away fast at the end. | Fading into a hard cut or a stop. Keeps the energy up until the last moment. |
| Logarithmic | Drops immediately, then trails off slowly. | Ducking under a vocal or an announcement. Gets out of the way at once and then disappears politely. |
A fade in and a fade out that would overlap are capped at half the file each, so you cannot accidentally fade a track to nothing. Everything is applied to a copy of the samples — your original file is never touched.
Frequently asked
Common questions
Can I fade a whole folder at once?+
Yes, and the bar-based lengths are what make it worth doing. Drop as many files as you like and "8 bars" is resolved against each file's own detected tempo — so a queue containing a 124 BPM house track and a 174 BPM drum and bass track both get eight bars, rather than both getting the same number of seconds and one of them being wrong. Switch to seconds if you actually want a fixed duration. The finished files come back as one archive.
Does my file get uploaded?+
No. The file is decoded, faded and written back out inside your browser tab. Open the network panel and watch it stay empty — there is no upload endpoint behind this page.
How does it know how many bars a fade is?+
The tempo is detected from the audio when you drop the file, and a bar is four beats at that tempo. The seconds equivalent is shown next to every bar button so you can see both. If no steady tempo is found — which happens on ambient material, live recordings and anything without a clear pulse — the bar buttons disappear and you set the length in seconds instead.
Why should a fade land on a phrase boundary?+
Because electronic music is built in blocks of 8, 16 and 32 bars, and a listener follows that structure whether or not they know it. A fade that begins at the top of a phrase reads as part of the arrangement. A fade that begins three beats into one reads as something going wrong. It is the same reason you start a mix on a phrase rather than wherever the track happens to be.
Can I fade only one end?+
Yes — set the other to zero, or use the "None" button. A fade in on its own is the usual fix for a track that starts abruptly or with a click; a fade out on its own is the usual fix for a recording that was stopped rather than ended.
Will a fade fix a click at the start of my file?+
Almost always, yes. A click at the very beginning is usually the waveform starting at a non-zero value, so the speaker has to jump there instantly. Even a very short fade in — a few milliseconds is enough — starts it from silence and the click goes. If the click is at the end instead, a short fade out does the same job. If the whole file sits off zero, that is a DC offset and the reverse tool measures it.
Does fading lose any quality?+
No. A fade multiplies each sample by a number between zero and one, which is exact arithmetic in the floating-point domain the tool works in. The only rounding happens when the result is written back to a fixed bit depth, and 16-bit output is dithered so the fade tail stays smooth rather than developing the gritty edge that undithered truncation produces at very low levels.
Why is the output only WAV and AIFF?+
Because writing a faded MP3 back out as an MP3 means encoding lossy audio a second time, which is real quality loss inflicted by a tool that was supposed to be helping. Both formats offered here are lossless and both play on every CDJ. If you need a smaller file, make it from this output at the very end of your chain.
Can I hear it before I download?+
Yes — a player appears with the processed audio as soon as it is ready, so you can check the fade before saving anything. Nothing is written to disk until you press download.
How long a file can I fade?+
Up to 800 MB, which is roughly 75 minutes of 24-bit stereo audio, so fading the ends of a recorded set works fine. The tempo detection gets coarser past about four minutes, so on a full set the bar buttons are a rough guide rather than exact.
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