Audio Trimmer
Upload an audio file and cut it down to just the part you need. Runs entirely in your browser — the file is never uploaded to a server. Downloads as a WAV file.
Click to upload or drag and drop
MP3, WAV, OGG, or other common audio formats
How it works
Your audio file is decoded into raw audio samples using the Web Audio API, then the samples between your chosen start and end points are copied into a new file and re-encoded as WAV. Nothing is uploaded — decoding, trimming, and encoding all happen in your browser.
Why the output is always WAV
WAV is an uncompressed format that's straightforward to generate reliably in a browser without extra dependencies. If you need MP3 specifically, most audio and video editing tools can convert a WAV file afterward.
How the trim is calculated
The Start and End sliders move in steps of 0.1 second. Each is multiplied by the audio's sample rate and rounded down to a sample position, and exactly that range is copied for every channel. If your browser decoded the audio at 44,100 Hz, a trim from 10 seconds to 40 seconds keeps samples 441,000 to 1,764,000, which is 1,323,000 samples. The times beside the sliders and the Trimmed length line are shown as minutes and seconds with fractions dropped.
How big the WAV will be
The output is 16-bit WAV: a 44-byte header plus 2 bytes per sample per channel. That 30-second stereo clip at 44,100 Hz comes to 44 + 1,323,000 × 2 × 2 = 5,292,044 bytes, about 5.05 MB, and the same clip in mono is 2,646,044 bytes. At 48,000 Hz the stereo clip is 5,760,044 bytes. The sample rate is whatever your browser decoded the file at, and a compressed MP3 of the same length is usually far smaller.
Defaults, errors and limits
When a file loads, Start is 0 and End is the full length, so pressing Trim without moving anything simply converts the whole file to WAV. If Start is not before End, the tool shows "Start time must be before end time." One continuous range is kept per run, files can be up to 50 MB, and the format has to be one your browser can decode.
Frequently asked questions
Why does the trimmed file download as WAV even if I uploaded an MP3?
The browser decodes any audio format it supports into raw samples, but re-encoding directly back to a compressed format like MP3 needs a dedicated encoder library. WAV is uncompressed and can be generated reliably without one, so that's what this tool outputs.
Is there a file size limit?
Files over 50 MB are rejected with a message. Even below that, long audio is decoded into raw samples, which takes far more memory than the compressed file, so very long recordings can still be slow.
How precise is the cut?
The sliders move in 0.1-second steps, and the cut lands on the exact sample for that time. If you need finer control than a tenth of a second, use an editor with a waveform view.
Can I remove the middle and keep both ends?
No. The tool keeps a single range between Start and End. To drop a middle section, trim the two ends as separate clips and join them elsewhere.
What happens if I press Trim without moving the sliders?
You get the whole file, converted to a WAV with the same name. Nothing is cut because Start is 0 and End is the full length.