Audio Trimmer & Converter - MP3, M4A, WAV
Cut a section out of an audio file and convert it between MP3, M4A, and WAV, without uploading anything.
Maintained by Hirantha Sandaruwan Lakshan. Updated 31 July 2026.
About this tool
Trims between two points of the same format are a direct copy of the audio data, so they finish in under a second even on an hour-long file.
How it works
The tool never fully decodes long files to raw audio in memory - a 30-minute stereo track decoded to raw samples needs well over half a gigabyte of RAM, enough to crash a mobile browser tab. Instead it streams through the file's encoded packets directly.
Trimming within the same format (MP3 in, MP3 out) is a packet copy: the encoded audio between your two points is copied byte-for-byte with no re-encoding, so there's no quality loss and no meaningful wait.
Converting to a different format re-encodes the audio - MP3 output goes through a real LAME encoder running as WebAssembly, the same encoder used by most desktop audio software.
Worked examples
Making a ringtone
Set an in-point and out-point around the section you want, keep the format as MP3, and the trim finishes almost instantly since it's a packet copy rather than a re-encode.
Converting a voice memo to MP3
iPhone voice memos save as M4A. Converting to MP3 re-encodes through the WebAssembly LAME encoder for compatibility with software that doesn't support M4A.
Extracting a clip from a podcast recording
WAV input can be trimmed and converted straight to MP3 in one step, skipping the need for separate editing software for a simple cut.
Output formats compared
| Format | Compression | Compatibility | Best for |
|---|---|---|---|
| MP3 | Lossy | Plays essentially everywhere | Sharing, ringtones, anything that has to just work |
| M4A (AAC) | Lossy | Apple devices, modern browsers | Better quality than MP3 at the same size |
| WAV | Uncompressed | Universal, but very large | Short clips headed into editing software |
Frequently asked questions
Does trimming lose audio quality?
Not when the input and output formats match - that case is a direct packet copy, not a re-encode. Converting between formats does re-encode, same as any audio converter.
Is there a length limit?
No hard limit, but very long files on mobile trigger a warning since phone browsers have limited memory. Desktop handles hour-plus files comfortably.
Does it keep cover art?
No - cover art is stored as an embedded video track, and MP3 output specifically discards it, since keeping it can silently break playback in some players.
Can I preview before downloading?
Yes, set your in and out points against the current playback position, or use the 'set to playhead' buttons while listening.
Is my audio uploaded anywhere?
No, the whole process runs in your browser tab and nothing is sent to a server.
What formats can I convert to?
MP3, M4A, and WAV as outputs. Inputs include MP3, M4A, WAV, OGG, and FLAC.
Can I fade the audio in or out?
Not currently. The trim is a clean cut at the points you set.
Does it work with M4A voice memos from an iPhone?
Yes. M4A is a supported input, and converting to MP3 is the usual reason people bring one here.
Sources & references
Updated Jul 31, 2026