Common reasons to cut audio
Most people who need an MP3 cutter want one specific slice of a longer recording: the chorus of a song for a ringtone, a quote from an interview, a clean intro for a podcast episode, the one take worth keeping from a voice memo, or a sound effect pulled out of a longer sample. You do not need a full audio editor for that. Two points in time, start and end, are enough.
How the cutter works
When you load a file, your browser decodes it and draws a waveform of the first channel, so you can see where the loud and quiet parts are. Silences show up as thin flat stretches, which makes it easy to find the gap between two sentences or the moment a beat drops.
Below the waveform are two sliders, Start and End, with a resolution of one tenth of a second. The selected length is shown underneath. The sliders cannot cross: dragging Start past End pushes End along with it, and vice versa. Use the built-in audio player to listen and note the timestamps before you set the sliders.
When you click Trim, FFmpeg running as WebAssembly in your tab cuts the selected range and encodes it as MP3 with the LAME encoder at a constant 192 kbps. Nothing is uploaded. The downloaded file keeps your original name with -trimmed.mp3 added, so you will not overwrite the source by accident.
Accuracy, quality and file size
Because the cut is re-encoded rather than copied, it lands exactly where you put the sliders instead of snapping to the nearest MP3 frame boundary. The trade-off is that the selected section goes through one more round of lossy compression.
What that means in practice:
- From WAV. Encoding uncompressed audio to 192 kbps MP3 is transparent for most listeners on most material. A one-minute stereo WAV of about 10 MB becomes roughly 1.4 MB.
- From MP3 at 128 kbps. The output is 192 kbps, but it cannot sound better than the source. The file just gets slightly larger than the equivalent slice of the original.
- From MP3 at 256 or 320 kbps. You lose a little headroom. For ringtones, voice clips and social posts this is inaudible; for an archival music master, keep the original.
Size is easy to predict at a constant bitrate: 192 kbps is 24 KB per second, about 1.4 MB per minute. A 30-second ringtone ends up near 720 KB. If you need something smaller, for example to fit an upload limit, compress the MP3 after cutting.
Practical tips for clean cuts
- Start a little early, end a little late. Cutting right on a waveform peak can chop off the attack of a word or drum hit. Leave 0.1 to 0.3 seconds of margin, which is one to three slider steps.
- Cut in silence. For speech, place both points in the flat gaps between sentences. You avoid half-syllables and audible clicks at the edges.
- Ringtones. Phones typically play the start of the file, so begin on the hook rather than on a quiet intro. 20 to 30 seconds is a sensible length; most ringtones are cut off before they finish anyway.
- Multiple pieces from one file. Trim, download, then adjust the sliders and trim again. The file stays loaded, so you can extract several clips in a row without re-adding it.
- Audio inside a video. If the sound you want is part of a video, first extract it as MP3, then cut it here.
Formats, limits and privacy
The cutter accepts MP3, M4A, WAV and OGG files up to 256 MB, which covers a multi-hour podcast in MP3 or roughly 25 minutes of uncompressed CD-quality WAV. Whatever the input, the output is always MP3, the format with the widest playback support across phones, car stereos, browsers and editing software.
The FFmpeg engine is about 30 MB and is downloaded on first use, then cached by the browser, so later trims start almost immediately. Very large files are held in memory during processing; if a phone runs out of memory on a long recording, try the same file on a desktop browser. Your audio never leaves the device, which is useful for unpublished music, confidential meetings or private voice notes.