You have a 40-minute interview and only need the 25 seconds where the guest says the exact line you want to quote. Opening a full desktop editor for that is overkill. A browser-based audio cutter solves this in two clicks, with nothing to install and nothing uploaded anywhere.
Two ways to cut audio, and they're not the same
When you trim a compressed file (MP3, OGG, AAC…), there are two ways to do it:
- Fast mode (copy): the tool finds the nearest valid cut point and copies the compressed data as-is, without decoding or re-encoding. It's near-instant.
- Precise mode (re-encode): decodes the audio, cuts at the exact sample you picked, and re-encodes the result.
The difference matters because compressed formats can't be cut at an arbitrary point. An MP3, for example, is internally split into audio frames of roughly 26 milliseconds each; a "fast" cut can only start or end at one of those frame boundaries, not the exact millisecond you asked for. For most uses (trimming a clip to share, removing trailing silence) that tens-of-milliseconds imprecision is inaudible. If you need the cut to land exactly where you marked it — say, to sync with video or music — use precise mode.
When to use each mode
Use fast mode when:
- You're trimming long clips and want the result instantly.
- The cut point doesn't need to be exact to the millisecond (speech, podcasts, voice notes).
Use precise mode when:
- You need the cut to start or end exactly where you marked.
- You're going to chain the result with another clip and a 20-30ms offset would be noticeable.
- The output format differs from the input (re-encoding is mandatory in that case anyway).
Supported formats
MP3, WAV, OGG, FLAC, M4A and AAC. WAV never has the fast-mode imprecision problem because it's uncompressed PCM — every sample sits at a fixed position, so the cut is always exact there regardless of mode.
How it's processed in the browser
This tool runs FFmpeg compiled to WebAssembly inside a browser tab. The file is never uploaded to a server: it gets decoded, cut and re-encoded using your own device's CPU. For long files (over an hour), precise mode can take a few seconds because it has to re-encode the whole audio, not just the trimmed part — the same cost you'd pay with any desktop editor.
Frequently asked questions
Why doesn't fast mode cut exactly where I placed the marker? Because it respects the compressed format's frame boundaries to avoid decoding anything. It's a technical limitation of the format, not a bug in the tool.
Do I lose quality when trimming? In copy mode, none — the compressed bytes are copied as-is. In precise mode it's technically re-encoded, but at a high quality setting (VBR ~V2 for MP3, for example) the loss is inaudible.
Is there a duration or size limit? No artificial limit imposed by the tool; the real limit is how much audio your own device can process.
Do I need to install FFmpeg? No, it downloads as WebAssembly the first time you use the tool and runs inside the browser.
Trim your audio for free, with nothing uploaded to any server, using the audio cutter: choose fast or precise cutting depending on what you need.