How to Fade Audio In and Out Online
Five steps, under a minute. Nothing to install, no account, and the file never leaves your device.
- Add your audio file — Drop an MP3, WAV, FLAC, OGG, M4A or AAC file onto the box, or click to browse. It is decoded locally and never leaves your device.
- Set the fade lengths — Drag the In and Out handles on the waveform, or use the sliders for exact values. The waveform redraws to show the faded result over a ghost of the original.
- Pick a curve — Equal power is the default and suits almost everything. Switch to S-curve for the smoothest musical fade, or linear if you need a predictable constant rate.
- Preview it — Press play to hear the fade applied in real time, with a playhead tracking the position. Adjust while it plays — the preview follows the sliders.
- Download — Choose MP3 for a small file or WAV to stay lossless. The fade is rendered offline and matches exactly what you previewed.
What Is a Fade In and a Fade Out?
A fade in is a gradual rise from silence to full volume at the start of a clip. A fade out is the mirror image at the end. Both are gain ramps — the audio itself is unchanged, only its level over time is scaled.
They exist because instant starts and stops sound wrong. A hard cut draws attention to the edit, and if the waveform happens to be mid-cycle at that edge it produces an audible click. A fade of even half a second reads as intentional; a few milliseconds is enough to kill the click without being heard as a fade at all.
Which Fade Curve Should You Use?
The curve is the shape of the ramp, and it changes the character of the fade more than the length does. Equal power is the default here and is the right answer for most material.
| Curve | Shape | Best for |
|---|---|---|
| Equal power | Sine law — bows above the straight line | Constant perceived loudness. The safe default, and the right choice before a crossfade. |
| S-curve | Raised cosine — eased at both ends | Eased at both ends. The smoothest, most musical fade for song intros and outros. |
| Linear | A straight line at a constant rate | Volume changes at a constant rate. Predictable, and what most editors do by default. |
| Exponential | Starts slow, then accelerates | Starts slow then accelerates. Good for dramatic swells and quick drop-outs. |
| Logarithmic | Rises fast, then plateaus | Rises fast then plateaus. Reaches a usable level early — handy under narration. |
Why Equal Power Instead of Linear?
A linear fade changes amplitude at a constant rate. That sounds like it should be the neutral choice, but human loudness perception is closer to logarithmic than linear, so a linear fade-out appears to hold near full volume for most of its length and then collapse at the very end.
Equal power follows a sine law instead. At the halfway point it sits at about 0.707 rather than 0.5 — a bow above the straight line that keeps perceived loudness constant across the ramp.
The difference becomes measurable rather than subjective when two fades cross. Two linear fades meeting at their midpoints put both signals at half amplitude, and two uncorrelated signals at −6 dB sum to −3 dB, not to unity — an audible dip in the middle of the transition. Equal-power curves satisfy a² + b² = 1 at every point, so the combined power stays flat. That is why it is the default here, and why it is the curve to pick if you are fading two clips to overlap them.
Why Does My Audio Click at the Start or End?
Because the file begins or ends part-way through a waveform cycle. A sample value of, say, 0.6 sitting immediately after silence is an instantaneous jump, and a speaker cone reproduces that vertical step as a click or thud. It is not a corrupted file and not an encoding fault — it is a discontinuity.
The fix is a fade so short you cannot perceive it as a fade. Eight milliseconds is roughly a third of one cycle of a low bass note: long enough to smooth the step, far too short to soften a transient. That is what the Remove clicks at the edges option does, and it is on by default because there is essentially no case where you want the click.
It is also applied intelligently: the micro-fade only touches edges where a longer fade is not already ramping, so switching it on can never reshape or shorten a fade you deliberately set.
Recommended Fade Lengths by Use Case
Fade length is a judgement call, but these are the conventions. Each row is available as a one-click preset in the tool.
| Use case | Fade in | Fade out | Curve | Why |
|---|---|---|---|---|
| Podcast | 0.5 s | 0.5 s | Equal power | Tightens the top and tail without losing momentum on the intro |
| Intro & outro | 2 s | 3 s | S-curve | Long enough to feel deliberate, short enough to keep attention |
| Song ending | — | 5 s | S-curve | The classic radio fade — the listener barely notices it start |
| Long fade-out | — | 8 s | Equal power | Slow enough to disappear under a sleep or study loop |
| De-click only | — | — | Equal power | Removes the pop at a hard cut without shortening the audio |
How the Fade Tool Works
The waveform shows the result, not the source
The filled waveform is your audio multiplied by the fade envelope, drawn over a ghost of the untouched original. The audio being removed is visible rather than described, so you can see exactly where the fade starts biting before you play anything.
Preview is not a re-render
Moving a slider does not rebuild the file. Playback runs through a gain node whose envelope is written from the same curve function the export samples, so dragging is instant and the preview cannot drift from the downloaded result. Adjust while it plays and the envelope re-arms from the current position rather than restarting the ramp.
Nothing is uploaded
Decoding, fading and encoding all happen through the Web Audio API on your own machine. That is a privacy property, but it is also why the tool is fast: there is no upload to wait for, and no queue behind other users.
Technical Specifications
| Fade types | Fade in, fade out, or both at once |
|---|---|
| Curve shapes | 5 — Equal power, S-curve, Linear, Exponential, Logarithmic |
| Default curve | Equal power, for constant perceived loudness |
| Fade length | 0 to 30 s per side, or half the clip, whichever is shorter |
| Adjustment step | 0.1 s by slider, drag, or arrow key (Shift for 1 s) |
| Click removal | Optional 8 ms micro-fade at both edges, on by default |
| Waveform | Shows the faded result over a ghost of the original, with draggable edges |
| Preview | Real-time gain automation — no re-render when you move a slider |
| Input formats | MP3, WAV, FLAC, OGG, M4A, AAC |
| Output formats | WAV (16-bit PCM) or MP3 (192 kbps) |
| Processing location | 100% in your browser — the file is never uploaded |
| Account required | None. No signup, no watermark, no usage limit |
Frequently Asked Questions
Is this audio fade tool free?
Yes. It is completely free with no account, no trial and no watermark. There is no file limit and no daily cap, because the work happens on your own device rather than on a server we pay for.
Can I fade in and fade out at the same time?
Yes. Both fades are independent and can be set together. If the two lengths would exceed the clip, they are scaled back proportionally so their shapes are preserved rather than overlapping and gouging a hole in the middle.
What is the best fade length for a podcast?
About 0.5 seconds at each end. That is enough to remove the abruptness without the listener noticing a fade, which keeps the intro's momentum. For music beds under narration, 1 to 2 seconds is more usual. The Podcast preset sets 0.5 s in and out.
How do I fade out a song at the end?
Set the fade out to about 5 seconds and use the S-curve or equal-power shape. That is the classic radio-style ending: long enough that the listener barely registers it beginning. The Song ending preset does this in one click.
Why does my audio click or pop at the start or end?
Because the file begins or ends mid-waveform. The signal jumps instantly from silence to whatever value the first sample holds, and your speaker reproduces that step as a click. An 8 ms micro-fade removes it and is far too short to hear as a fade. The 'Remove clicks at the edges' option does this and is on by default.
Which fade curve sounds the most natural?
Equal power for most material, S-curve for music. A linear fade is linear in amplitude, but loudness perception is closer to logarithmic, so a linear fade-out seems to hold full volume and then collapse at the end. Equal power follows a sine law that keeps perceived loudness constant across the ramp.
Does the tool upload my file?
No. The file is decoded, faded and re-encoded entirely in your browser using the Web Audio API. Nothing is transmitted, so there is no privacy exposure and no wait for an upload — which is also why large files are fast.
Can I fade a WAV file without losing quality?
Yes. Export as WAV and the output stays 16-bit PCM with no lossy re-encoding. Choose MP3 only when you want a smaller file; it re-encodes at 192 kbps. Some free fade tools output MP3 only, which silently degrades a lossless source.
What is the longest fade I can apply?
Up to 30 seconds per side, or half the clip length if the file is shorter than that. Lengths are adjustable in 0.1 second steps by slider, by dragging the waveform handles, or with the arrow keys.
Does it work on a phone?
Yes. It works in iOS Safari and Android Chrome, and the waveform handles are sized for touch. Audio has to be started by a tap because mobile browsers block autoplay, which is what the play button does.
Can I use this to crossfade between two tracks?
Not in one step — this tool fades a single file. To crossfade manually, fade out the end of the first track and fade in the start of the second using the equal-power curve, then overlap them in your editor. Equal power is the correct choice there because two linear fades crossing produce an audible dip.
Which audio formats are supported?
MP3, WAV, FLAC, OGG, M4A and AAC in, and WAV or MP3 out. Anything your browser can decode will load; Chrome, Edge, Firefox and Safari all handle this set in their current versions.