Audio Trim & Join
Trim the part of an audio file you need, or join several clips, and save as WAV. Runs in your browser with no upload.
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Audio Trim & Join: complete guide
Walk through the steps and examples, or jump straight to the topic you need.
At a glance
- How it works
- WAV sound values are copied as they are; other formats are decoded and written out again as WAV.
- Saved format
- The result is always a 16-bit WAV. Even if the original is an MP3, it is not returned as an MP3.
- Trimming
- Cuts are aligned to sample boundaries, so no noise appears at the join.
- Joining
- The sample rate, number of channels and bit depth must all match. If they do not, the tool tells you which file differs.
- Limits
- Up to 10 files at a time and up to 100 MB each.
- Files that cannot be opened
- If the browser cannot decode a file into sound, it is not treated as a success and you are told so.
- Where it runs
- Everything from reading to saving happens in this browser.
How to use Audio Trim & Join
Add your sound files
WAV is read as it is, and MP3, M4A and others are converted to WAV when read. Files read after conversion are marked as such.
Choose between Trim and Join
Trim sets the part to keep from one file. Join links files in list order, and you change the order with the up and down buttons.
Set the range
Enter the start and end in seconds or as minutes and seconds like 01:05.3. If the end is before the start or past the length, the reason is shown and nothing is made.
Listen and save
Check the result in the player and then save it. The saved name includes the original name and what was done.
What it’s good for
Keeping only the part of a recording you need
Add a file and enter the start and end of the part to keep, and only that part is made into a new file. You can enter times in seconds or as minutes and seconds like 01:05.3. The cut position is aligned to a sample boundary of the sound, so there is no click at the join.
WAV and compressed files give different results
If you add a WAV, the sound values are copied as they are, so the quality does not change. MP3 and M4A files are decoded to sound by the browser and then saved again as WAV. So the result is not the same MP3 as the original, and the file gets larger. The screen tells you this in advance.
Worked examples
Keeping only the middle 0.5 seconds of a 1-second sound
8,000 Hz mono WAV, 1.0 s
Start 0.25 · End 0.750.5 s WAV
The sound values are byte-for-byte the same as the original sectionJoining two files
1.0 s + 0.5 s (both 8,000 Hz mono)1.5 s WAVResults by original format
Swipe the table sideways to see the rest.
| Original | Processing | Quality |
|---|---|---|
| WAV | Sound values copied as they are | Does not change |
| MP3, M4A and others | Decoded, then saved as WAV | The result of decoding once; it is not the original compressed file |
| Compressed WAV | Decoded, then saved as WAV | Same as above |
When the result isn’t what you expected
The Join button cannot be clicked
Files with different sample rates or numbers of channels are mixed in. The screen shows which file differs and how, so remove that file or match it to the same conditions and try again.
The saved file is larger than the original
When you add a compressed file such as an MP3, it is saved as the decompressed WAV. If file size matters, compress the saved WAV again with a separate conversion tool.
The browser cannot open the file
The sound formats a browser can decode differ from browser to browser. A file that could not be opened is not treated as a success and is reported with its name. Try another browser, or convert the file to WAV and add it again.
The cut position is slightly different
Sound can only be cut at sample positions, so the cut is aligned to the sample boundary nearest the time you entered. For an 8,000 Hz file, the difference is at most 0.000125 seconds.
Key terms
- Sample rate
- How many times per second the sound was recorded. 44,100 Hz is common.
- Channel
- Mono has 1 and stereo has 2. They must match to join files.
- Lossless
- Moving the sound values as they are, without compressing them again.
Audio Trim & Join FAQ
If I add an MP3, is it saved as an MP3?
No. It is saved as WAV. Re-creating an MP3 in the browser alone would compress it once more and lower the quality, so it is kept as uncompressed WAV and the screen says so.
Are there conditions for joining several files?
The sample rate, number of channels and bit depth must all be the same to join them as they are. If they differ, the tool tells you which file differs and how, so match them to the same conditions and try again.
Is my file uploaded to a server?
No. Reading, trimming, joining and saving all happen inside this browser.
Can I change the volume?
For now it only trims and joins. Volume adjustment and fades are not included.
Can I delete just the middle part?
It keeps only one section at a time. If you trim the beginning and the end separately, save them and then join them, the result is the same as removing the middle.
Are my files saved?
No. Refreshing clears the list, so save the files you make first.