2Drag the start and end handles on the waveform or the timeline, or type exact timecodes if you already know them.
3Preview the selection and run the cut — the part you keep is copied through untouched wherever the format allows it.
4Download the trimmed AAC file.
AAC Cutter FAQ
How does AAC Cutter cut the file?
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Concretely, the cut is made on frame boundaries and the surviving frames are copied through without re-encoding, so the audio you keep is bit-identical to the original — no second generation, and the job finishes in about the time it takes to upload. You set the start and end points on the waveform or the timeline and keep what is between them.
How precisely can I place the start and end points?
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You can type exact timecodes rather than only dragging, and the preview scrubs to the position as you move it. How exact the result can be depends on the format: some allow a cut anywhere, others snap to the nearest frame or keyframe.
Does the format limit where I can cut?
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It does. AAC is the MP4-family lossy codec, audibly better than MP3 at the same bitrate and the default for Apple devices. That is precisely what decides whether a cut can be placed arbitrarily or has to land on a structural boundary.
Anything specific to AAC when trimming?
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Yes — AAC carries encoder delay in the container, so a naive cut can leave a few milliseconds of silence that a proper trim removes. It explains most of the "the cut is a fraction of a second off" surprises.
Can I remove a section from the middle instead of keeping one?
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Yes — cut the piece before it and the piece after it, then merge the two results. That is deliberately two steps because it keeps both halves on the fast, lossless path instead of forcing a full re-encode.
Is the part I keep re-encoded?
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Not if the format allows a stream copy — the data you keep is bit-identical to the source and the job finishes in about the time the upload took. Only a frame-exact cut on a format that cannot do it cheaply needs a re-encode.
What can I upload to AAC Cutter?
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MP3, AAC, M4A, OGG, Opus and WMA are the lossy codecs handled directly, and lossless sources (WAV, FLAC, AIFF) can go in the same batch. The codec is probed from the stream, so an incorrectly named file still works.
Is there a file size limit on AAC Cutter?
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Yes: free accounts process audio up to 200 MB per file, which at typical bitrates is several hours of material; ffmpeg does the decoding and encoding, exactly as it would on a desktop. That is the most generous cap on the site after video, and audio work rarely runs into it.
Will AAC Cutter lower the quality of my AAC audio files?
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A lossy file has already discarded detail once, and re-encoding discards more — that is generation loss and it does not undo. Wherever the job can be completed by copying the encoded stream rather than re-encoding it, that is what happens, and the audio comes back bit-identical.
Can I run AAC Cutter on several AAC audio files at once?
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Yes. Upload the set and they process in parallel with the same settings, which is the practical way to handle a podcast series or an album rather than repeating the job by hand.
Do tags and cover art survive?
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Yes. ID3, Vorbis comments and MP4 metadata atoms are carried across, cover art included, so a processed file still sorts correctly in a music library. ReplayGain values are recalculated rather than copied, because a stale one is worse than none.
Does AAC Cutter cost anything?
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No. AAC Cutter is free without an account and adds no audio watermark or spoken tag to the output. Your upload is deleted from the workers shortly after the job completes.
