Audio Trimmer & MP3 Cutter — Free, Browser-Based
Trim an audio file down to just the part you need: drag the handles on the waveform or type exact timecodes, preview the selection, add optional half-second fades, and export MP3 or WAV. Powered by ffmpeg.wasm, entirely on-device.
Private by design. Your audio is decoded, previewed, and trimmed entirely in your browser via ffmpeg.wasm — nothing is uploaded to a server.
FreeNo sign-upRuns in your browserMultimediaApplication
Lossless copy vs. re-encode — what happens to your audio when you trim
This tool picks the best ffmpeg strategy automatically based on your input format, output format, and whether fades are enabled. Knowing which path you are on tells you exactly what happens to quality and speed.
| Scenario | What ffmpeg does | Quality | Speed |
|---|---|---|---|
| MP3 → MP3, no fades | Stream copy (-c copy) — cuts at frame boundaries, no decode | Lossless, bit-identical frames | Near-instant |
| MP3 → MP3, with fades | Decode → afade filter → re-encode at 192 kbps | One extra lossy generation (transparent for most listeners) | Seconds |
| Any format → WAV | Decode → optional fades → 16-bit PCM | Lossless output (source quality preserved) | Seconds |
| M4A/OGG/FLAC → MP3 | Decode → optional fades → re-encode at 192 kbps | One lossy generation | Seconds |
- Audio has no keyframes, so unlike video trimming there is no "snap to keyframe" problem — cuts land within one codec frame (~26 ms for MP3) of your chosen timecode.
- WAV output is roughly 10 MB per minute (stereo 44.1 kHz) versus about 1.4 MB per minute for 192 kbps MP3 — pick WAV when you plan further editing, MP3 for sharing.
How to trim an MP3 or audio file in your browser
- Drop your audio file. Drag in an MP3, WAV, M4A, AAC, OGG, or FLAC. The file decodes locally and a waveform of the whole track appears.
- Set the trim range. Drag the orange start/end handles directly on the waveform, or type exact mm:ss.s timecodes. The selected region is highlighted.
- Preview and add fades. Click Preview selection to hear exactly what you will export. Toggle 0.5s fade-in and fade-out for smooth edges — great for ringtones.
- Export MP3 or WAV. Pick a format and click Trim & Export. MP3-to-MP3 trims without fades are lossless stream copies; everything else re-encodes at 192 kbps MP3 or 16-bit WAV.
Frequently Asked Questions
- Is my audio uploaded?
- No. Decoding, waveform rendering, and trimming all happen in your browser via the Web Audio API and ffmpeg.wasm. The file never leaves your device.
- Does trimming reduce audio quality?
- Trimming an MP3 to MP3 with no fades uses a lossless stream copy — zero quality loss. Adding fades or converting formats re-encodes (192 kbps MP3 or lossless 16-bit WAV).
- What formats can I trim?
- Input: MP3, WAV, M4A, AAC, OGG, and FLAC — anything your browser can decode. Output: MP3 or WAV.
- How accurate is the cut?
- Within about 0.1 seconds. MP3 frames are ~26 ms long and audio has no keyframes, so cuts land essentially where you set them — unlike video trimming.
- Why does the first export take a moment?
- The first export downloads the ffmpeg.wasm engine (~31 MB, cached afterwards). Subsequent trims start instantly.
- Can I make an iPhone ringtone with this?
- Trim to under 30 seconds with a fade-out and export. iPhones need M4R (AAC) for ringtones, so convert the exported file with GarageBand or iTunes/Finder as a final step.
Use Cases
- Cut a chorus out of a song for a ringtone or alarm sound
- Trim silence or dead air from the start and end of a recording
- Extract one answer from a long interview or lecture recording
- Slice a podcast highlight for a social clip
- Shorten a sound effect and add a fade-out for a video project