How to fade audio in or out
- Choose an audio file.
- Set the fade-in and fade-out lengths in seconds. Set either one to 0 to leave that end as it is.
- Pick a curve: Linear, Exponential or S-curve. The coral line over the waveform shows the result.
- Press Play start or Play end to hear each fade, and adjust until it sounds right.
- Choose MP3 or WAV and press Download.
Which fade curve to choose
| Curve | How the volume changes | Good for |
|---|---|---|
| Linear | By the same amount every moment | Very short fades that remove clicks |
| Exponential | By the same number of decibels every second | Long fade-outs at the end of a song; fade-ins that sound even |
| S-curve | Gently at both ends, faster in the middle | Fades of a second or two on music or speech |
A linear fade can sound uneven because hearing responds to ratios. Halfway through a linear fade-out the amplitude is down by half, which is only 6 dB quieter, so the first part of the fade seems slow and most of the audible drop happens in the last moments. The exponential curve here spreads about 40 dB of reduction evenly across the fade before it reaches silence, so the volume seems to fall at a steady rate.
How long should a fade be?
- 5 to 20 milliseconds (0.005 to 0.02 s): enough to remove the click you hear when audio starts or stops abruptly. You won't hear it as a fade.
- 0.5 to 2 seconds: intros and outros for podcasts, voice memos, ringtones and short clips.
- 3 to 10 seconds: the classic fade-out at the end of a song.
These are starting points. The preview buttons play each fade with a few seconds of context, which is the quickest way to judge it.
Why cuts click, and how fades fix it
A sound wave is rarely at zero at the exact point where a file starts or stops. If playback jumps from silence straight into the middle of a waveform, the speaker has to move instantly and you hear a click or pop. A fade, even a few milliseconds long, ramps the level up from zero so the edge is smooth. That's also why a short fade helps after trimming a file in the Audio Cutter.
Frequently asked questions
- Can I fade only the end of a song?
- Yes. Set the fade-in to 0 and choose the fade-out length. The start of the file stays exactly as it was.
- What if the fades are longer than the file?
- Each fade is limited to the length of the file. If the fade-in and fade-out together are longer than the file, they overlap and multiply, so the middle never reaches full volume. The tool warns you when that happens.
- Does fading change the rest of the audio?
- No. Only the samples inside the fades are changed, and everything between them keeps its level. Saving as MP3 does re-encode the whole file, though, so choose WAV if you'll keep editing it.
- Which curve is best for the end of a song?
- Exponential is the usual choice for long fade-outs because the volume seems to fall at a steady rate. For a fade of a second or two, the S-curve often sounds smoothest.
- Is my file uploaded?
- No. The fades are calculated in your browser, and your files never leave your device.
Your files never leave your device. Everything on this page runs locally in your browser: there's no upload, no account and nothing stored on a server.