How to merge MP3 and other audio files
- Drop two or more audio files into the box. You can add more files at any time, in any order.
- Drag files by the handle, or use the up and down arrows, to set the playback order.
- Set a crossfade in seconds to blend each track into the next, or leave it at 0 for a straight join.
- Choose MP3 or WAV and click Join files to download joined-audio.
What you can do with Audio Joiner
- Mix formats freely
- Combine MP3, WAV, M4A, OGG and FLAC in one job. Everything is decoded to the same sample rate before joining.
- Drag-and-drop ordering
- Reorder tracks by dragging or with arrow buttons, and see each file's length and the total running time.
- Equal-power crossfade
- Blend tracks over up to 15 seconds using a smooth sine and cosine curve that avoids a volume dip in the middle.
- Mono and stereo together
- Mono clips are placed on both channels when joined with stereo files, so nothing ends up playing in one ear.
- Single output file
- Get one continuous MP3 (96 to 320 kbps) or WAV, ready for a playlist, slideshow or podcast episode.
Joining audio files and choosing a crossfade length
Joining files is useful for building a continuous mix, stitching together a podcast intro, interview and outro, combining voice memos recorded in parts, or making one track for a video slideshow. The joiner decodes every file to uncompressed audio, places them end to end and encodes the result once, so mixing formats such as an M4A from a phone with an MP3 and a WAV works without converting anything first. The total length is shown before you join, which helps when you need to hit a target duration.
A crossfade overlaps the end of one track with the start of the next while one fades out and the other fades in. Two to four seconds suits most music, half a second to one second smooths spoken segments without overlapping words, and 0 gives a gapless, back-to-back join for live albums or audiobook chapters. The crossfade is capped at half the length of the shortest file and shortens the total by its length at each joint. To remove silence at the start or end of a clip, trim it with the MP3 Cutter first.
Frequently asked questions
How do I merge MP3 files into one?
Drop the MP3 files into the joiner, arrange them in the order you want, and click Join files. The tool combines them into a single track and downloads it as joined-audio.mp3, or as a WAV file if you choose lossless output.
Are my files uploaded when I join them?
No. All files are decoded, joined and encoded in your browser, so nothing is sent to a server. That also means there's no upload wait, even when you combine long recordings or a full album.
Can I join files with different formats or sample rates?
Yes. Each file is decoded to your browser's audio sample rate before joining, so you can merge an M4A, an MP3 and a WAV recorded at different rates. The output uses that common rate, usually 44.1 or 48 kHz.
Is there a limit on how many files I can join?
You need at least two, and there's no fixed maximum. All files are held in memory as uncompressed audio, roughly 20 MB per stereo minute, so joining several hours of audio on a phone may be slow or run out of memory.
Does the audio joiner add gaps between tracks?
No. With the crossfade set to 0, each file starts on the exact sample after the previous one ends. Any silence you hear is already in the files; trim it with the MP3 Cutter if you want a tighter join.