MP3 — or M4A, WAV, FLAC, OGG and Opus. Everything is joined in your browser — nothing is uploaded.
About merging MP3 files
You have several MP3 files and want one: chapters of an audiobook, parts of a recording, songs for a mix, voice notes from one day. This tool joins them into a single MP3, in the order you choose.
Add the files, move them up or down, and press Merge into one MP3. Everything happens in your browser — your files are never uploaded.
Features
- One MP3 out — 128 to 320 kbps, or a WAV if you prefer
- Any order — move files up and down, or remove one, before you join
- Mixed files are fine — different bitrates, sample rates, mono and stereo
- Gap or fade — silence between files, or a short fade at each join
- Volume, if you want it — match the loudness, or leave every file as it is
- Private — joined on your device, never uploaded
Joined or re-encoded?
Some joiners glue MP3 files together frame by frame. That is fast, but it only works when every file has the same bitrate and sample rate, and you often hear a click or a short gap at each join.
This tool works differently, and it says so: every file is decoded to plain sound, the sound is joined, and the result is encoded once into a new MP3. That is why:
- Files with different bitrates and sample rates can be joined (a 22 kHz voice memo next to a 48 kHz song plays at the right speed),
- A mono file next to a stereo one works (it plays in both ears),
- There is no extra silence at the joins, and the gap or fade you choose is exact. (If a file stops in the middle of a sound, a fade of 0.1 s takes away the small click.)
The cost is one more round of MP3 encoding. At 192 kbps or more it is very hard to hear. As a rule, choose the bitrate of your best file, or higher.
How big will the merged MP3 be?
The size depends only on the total length and the bitrate you pick: bitrate × length ÷ 8. Gaps count as length too.
| Total length | 128 kbps | 192 kbps | 256 kbps | 320 kbps |
|---|---|---|---|---|
| 10 min 30 s | 10.08 MB | 15.12 MB | 20.16 MB | 25.2 MB |
| 30 minutes | 28.8 MB | 43.2 MB | 57.6 MB | 72 MB |
| 1 hour | 57.6 MB | 86.4 MB | 115.2 MB | 144 MB |
| 3 hours (an audiobook) | 172.8 MB | 259.2 MB | 345.6 MB | 432 MB |
1 MB = 1,000,000 bytes. Example: three songs of 3:30, 4:05 and 2:55 add up to 10 minutes 30 seconds. At 192 kbps the merged MP3 is 15.12 MB, whatever the bitrates of the three files were.
The volume choice
- Leave the levels alone — the default here. A plain join; each file keeps its own volume. Right for parts of one recording or an album.
- Match loudness between files — each file is measured, and quiet files are brought up to the loudest one. Good for voice notes or songs from different sources.
- Bring each file to a peak level — each file's loudest point goes to the target you set.
Whatever you choose, the finished sound is checked once at the end. If anything would go past the maximum, the whole result is turned down a little, so it does not crackle.
What people use it for
- Joining audiobook chapters into one file for a player with no playlist
- Putting recording parts together — a talk, an interview or a lesson split by the recorder
- Making one continuous mix of songs for a party, a workout or a video
- Combining voice notes into one message
- Adding an intro and an outro to a podcast episode
Good to know
- The merged MP3 has no title or artist tags. Add them with the MP3 Tag Editor.
- Every file is decoded into memory, and the result is built in memory too. One hour of stereo sound is about 1.4 GB of decoded samples (48,000 × 2 channels × 4 bytes × 3,600 s), so very long merges need a computer with plenty of memory. A phone is fine for shorter jobs.
- The MP3 encoder (about 170 KB) downloads the first time you merge to MP3, so the first merge needs a connection.
- Want only part of a file? Cut it first with the MP3 Cutter.
Frequently asked questions
Will the merged MP3 lose quality?
A little, because the joined sound is encoded once more. At 192 kbps or higher, almost nobody can hear it. If you need no loss at all, choose WAV as the output.
Can I join MP3 files with different bitrates?
Yes. Each file is decoded first, so the bitrates and sample rates do not need to match. The merged file uses the bitrate you pick.
How many files can I merge?
There is no fixed limit. The limit is your device's memory: the whole merged sound is held in memory before it is saved.
Are my files uploaded?
No. The files are read, joined and encoded inside this page, on your own device.
Related tools
- Audio Merger — the same joiner, with a WAV file out
- MP3 Cutter — cut each file before you join them
- MP3 Tag Editor — give the merged MP3 a title and cover
- MP3 Volume Booster — make the finished MP3 louder
- Merge Video — join video clips instead
How to use it
- Click Add MP3 files and pick all the files at once (you can add more later)
- Put them in order with the arrows, and remove any you do not want
- Leave MP3 and 192 kbps, or choose another quality
- Set a gap or a fade if you want one, and the volume choice
- Press Merge into one MP3, wait for the bar, then download the file
