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How to merge MP3 files into one track

Merging means joining two or more audio files end to end so they play as a single continuous track. It's how you stitch together recorded segments, combine a multi-part voice memo, or assemble a seamless mix. AudioTrim does it in the browser by appending files one after another — no uploads, no conversion software.

This guide uses the free AudioTrim editor. It handles MP3, WAV, M4A and OGG, and it automatically matches sample rates so files recorded on different devices still join cleanly.

Step by step

Open the first file. Drag your starting track onto audiotrim.app. This becomes the beginning of your merged track.
Append the next file. Click Append file and choose the second audio file. It's added onto the end of the first, and the waveform grows to show the combined length.
Repeat for each file. Keep clicking Append file to add as many tracks as you like, in the order you want them to play.
Check the joins. Press Play and listen at each boundary. If two files have very different volumes, click Normalize to even them out across the whole track.
Smooth the transitions (optional). For a polished result, you can fade individual sections before appending, or add a fade in at the very start and a fade out at the very end of the merged track.
Download. Export the combined track as a single MP3 (choose 192 or 320 kbps) or WAV.

Tip: Order matters — files are appended in the sequence you add them. If you want a specific running order, append them in that order. To rearrange, use Undo to step back, or start over with Reset.

Matching sample rates and channels

Audio files carry a "sample rate" (like 44.1 kHz or 48 kHz) and a channel count (mono or stereo). When you join files with mismatched settings, naive tools can produce speed or pitch glitches at the seam. AudioTrim resamples appended files to match the first one automatically, so a 48 kHz phone recording and a 44.1 kHz download will line up correctly. If you need everything in mono or stereo, use the Channels tools (Stereo → Mono or Mono → Stereo) before exporting.

Frequently asked questions

How many files can I merge?

There's no fixed limit — you can keep appending. Very large totals depend on your device's available memory, since all processing is local.

Can I merge files of different formats?

Yes. You can append an MP3 after a WAV after an M4A; they're decoded to a common format internally and exported together.

Will there be a gap or click between files?

Files are joined directly with no inserted gap. If a source file has silence at its start or end, trim it first. A short fade at each join removes any click.

What's the best export setting?

For music, 320 kbps MP3 or WAV. For voice, 128–192 kbps MP3 keeps the file small.

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