# Audio Trimmer & Converter - MP3, M4A, WAV

Page: https://hirantha.me/tools/audio
Part of: Hirantha Sandaruwan Lakshan free tools (https://hirantha.me/tools)
Updated: 2026-07-31

Cut a section from an audio file and convert it to MP3, M4A, or WAV.

This is a free tool that runs in the browser: open the page to use it. File tools process files on the visitor's own device; files are never uploaded or stored. No account, sign-up, payment or watermark.

Cut a section out of an audio file and convert it between MP3, M4A, and WAV, without uploading anything. 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.

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.

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 |

Q: Does trimming lose audio quality?
A: 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.

Q: Is there a length limit?
A: No hard limit, but very long files on mobile trigger a warning since phone browsers have limited memory. Desktop handles hour-plus files comfortably.

Q: Does it keep cover art?
A: 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.

Q: Can I preview before downloading?
A: Yes, set your in and out points against the current playback position, or use the 'set to playhead' buttons while listening.

Q: Is my audio uploaded anywhere?
A: No, the whole process runs in your browser tab and nothing is sent to a server.

Q: What formats can I convert to?
A: MP3, M4A, and WAV as outputs. Inputs include MP3, M4A, WAV, OGG, and FLAC.

Q: Can I fade the audio in or out?
A: Not currently. The trim is a clean cut at the points you set.

Q: Does it work with M4A voice memos from an iPhone?
A: Yes. M4A is a supported input, and converting to MP3 is the usual reason people bring one here.

Sources: MP3 (MPEG-1 Audio Layer III) (https://en.wikipedia.org/wiki/MP3); Advanced Audio Coding (AAC) (https://en.wikipedia.org/wiki/Advanced_Audio_Coding); WebCodecs API - MDN (https://developer.mozilla.org/en-US/docs/Web/API/WebCodecs_API)

Related tools:

- [Video compressor](https://hirantha.me/tools/video.md): Shrink a video so it's small enough to email or message.
- [Image compressor](https://hirantha.me/tools/image.md): Shrink a photo or convert it between JPG, PNG, and WebP.
- [MP4 to MP3 converter](https://hirantha.me/tools/mp4-to-mp3.md): Extract the audio from a video file as an MP3.
- [WAV to MP3 converter](https://hirantha.me/tools/wav-to-mp3.md): Convert a WAV file to a much smaller MP3.