Free Audio Trimmer

Worked example

Press "Try a sample" to add sample-audio.wav, a 12-second track. The waveform appears with the whole clip selected, and "Encoder ready" shows once the encoder has loaded. Type 3 into the "Start" box and 8 into the "End" box, pressing Enter after each. They read 0:03.0 and 0:08.0, and the line beside the waveform says "5.0s of 0:12.0". "Save as" is on "Keep original (lossless)" and no fade is ticked, so the note says the selection is copied out untouched. Press "Trim audio". The page shows "Trimmed clip ready — 5.0s" and the size, about 861 KB, because 16-bit stereo WAV at 44.1 kHz is 176,400 bytes a second. The file is named sample-audio_trimmed.wav. Now switch to "Cut out selection": the line reads "removing 5.0s, 7.0s left" and the button becomes "Cut out and join".

Which settings to use, and the limits

• Choose "Keep selection" or "Cut out selection" first. "Keep selection" is the default and saves only the part between Start and End. "Cut out selection" removes that part and joins what is left, which is the way to take out an ad, a cough or a mistake. The button then reads "Cut out and join". When the cut is in the middle, "Short crossfade at the join" is ticked by default; it lasts at most 0.15 seconds, and less if either remaining piece is very short. A cut always re-encodes the audio.
• Set the range by dragging, typing or nudging. Drag a handle on the waveform, drag the shaded middle to move the whole selection, or click to move the playhead. In the "Start" and "End" boxes type 75.5, 1:15.5 or 1:02:03.5 (a comma also works as the decimal point) and press Enter. The "−" and "+" buttons move 0.1 second, and "Set start at playhead" and "Set end at playhead" take the time from the playhead. The sliders step 0.05 seconds for clips up to 2 minutes, 0.1 up to 10 minutes, 0.5 up to an hour and 1 beyond. The selection is never shorter than 0.1 seconds.
• Leave "Save as" on "Keep original (lossless)" for a plain trim. With "Keep selection" and no fade ticked, the audio is copied out without re-encoding. It is instant, the quality is identical, the file keeps its own format, and the download is named like name_trimmed.mp3. Tick "Remove tags and cover art" to leave the title, artist and artwork out of the output. A fade, "Cut out selection" or a different format under "Save as" re-encodes instead, and the note above the button turns to a warning to say so.
• Pick the format and quality when you re-encode. "Save as" offers MP3, WAV, M4A, FLAC and OGG. WAV and FLAC are lossless, so they have no "Quality" menu. For the others, "Same as source" matches the source bitrate rounded up to a standard step, never above 256 kbps (192 for OGG), and "High (256 kbps)" uses that top figure. "Fade in" and "Fade out" take a "Fade length" of 0.5, 1, 1.5, 2 or 3 seconds, never more than half the clip. If you keep the original type, MP4, AAC, M4B, MOV and 3GP sources become M4A, Opus becomes OGG, and unknown types become MP3.
• Know what a large file does. The tool cuts one file by reading it in place instead of copying it into memory, so a long recording costs the trim almost nothing. The waveform is skipped if decoding the file would not fit; use the time boxes instead. If the engine cannot read the file in place, a file above about 2 GB is refused (1 GB on a computer reporting 4 GB of memory or less, 400 MB on a phone). The first use downloads the encoder, about 31 MB. The "Trim audio" button stays pinned to the screen, and the page scrolls to it after you add a file if it was hidden.
• Play the selection before you commit. "Play selection" plays from Start to End and stops at End. If the playhead is already inside the selection, it resumes from there. In "Cut out selection" mode it still plays the part that will be removed, not what will remain. After trimming, a player appears for the result and "Trim again" runs it once more with the current settings. Below it are buttons to pass the file on to other tools, such as "Normalize volume", "Transcribe" or "Add music".

Common problems and how to fix them

It says "This conversion failed — the chosen format or codec may not be supported for this input. Try a different output format, or a different source file."

The encoder could not write what was asked from this input. A plain trim copies the audio into the file's own container, and that fails for some unusual files. Choose a format under "Save as" that differs from the file's own type, or tick a fade, and the tool decodes and re-encodes the clip instead. If that fails too, convert the file with the Audio Converter first.

It says "This file couldn't be read — it may be incomplete (still downloading or only partly copied) or not a real video/audio file. Try the original file again."

The encoder found the file's header or index missing or invalid, which is typical of a download that has not finished, a file that was only partly copied, or something that is not audio at all. Wait for the copy or download to finish, or fetch the original again, and add it again.

It says "Couldn't read this audio file — it may be corrupted or in an unsupported format. Try converting it with the Audio Converter first."

This replaces the waveform when the browser could not decode the file, its audio player gave no length within 4 seconds, and the encoder could not find one either. With no length there are no handles or sliders, so nothing can be trimmed. Convert the file to MP3 or WAV in the Audio Converter, then add the converted copy.

It says "Couldn't render a waveform for this file, but you can still trim it using the time controls below."

The browser could not decode the file to draw it, or decoding it would use more than half of the tab's memory budget, as with a multi-hour recording. The trim does not need the waveform. Type the times into "Start" and "End" or use the sliders, check with "Play selection", and press "Trim audio".

It says "This file changed or moved after you picked it — please choose it again."

The trim reads the file in place while it runs, so a file that was moved, renamed, deleted or saved over after you picked it cannot be read. The page checks before it starts and tells you instead of failing part-way. Remove the file and add it again from where it is now.

How it compares

A desktop audio editor can work on many tracks, apply effects and make several cuts in one session. This tool cuts one range at a time: it keeps it or cuts it out, with optional fades, a short crossfade at a join, a format change and tag removal. It cannot make several cuts in one pass. The lossless copy is fast and exact in quality, while re-encoding to MP3, M4A or OGG re-compresses the sound slightly. In exchange nothing needs installing, and the audio is processed in your browser, not uploaded.