Audio Joiner (Merge MP3 Files)

Merge several songs, voice notes or podcast parts into one file. Put them in order, add silence between them or blend them with a crossfade, even out their loudness, and save the result as MP3, WAV or M4A. Files that share the same format can also be joined without re-encoding. Everything happens in your browser, so nothing is uploaded.

How to use this tool

1. Select the files in the order they should play (or choose "By file name").
2. Optionally set a gap, or a crossfade for a DJ-style blend; tick "Match loudness" if the files differ in volume.
3. Choose the output format and press Calculate.
4. Check the timing table, play the result and download it.

Formula

Total = Σ lengths + gap × (files − 1) − crossfade × (files − 1)

All files are decoded to one common sample rate (the highest among them, at most 48 kHz) and channel count. A crossfade uses equal-power curves (sine and cosine), which keep the loudness steady while the two overlap. "Match loudness" compares the average level of each file's non-silent parts and moves every file to the median, without letting any of them clip. The lossless mode and M4A output use the ffmpeg engine (about 30 MB, downloaded once).

Example

Three tracks of 3:00, 2:30 and 4:00 joined with 2-second crossfades last 180 + 150 + 240 − 2 × 2 = 566 s (9:26). With a 1-second gap instead it would be 570 + 2 = 572 s.