OneTaskBy Tim King · Updated
Left/Right Channel Extractor
Split Stereo Audio Into Left and Right Mono Files, or Keep Just One Side
OneTask is free, with no sign-up, and built by one person.
If this tool saved you time, a coffee helps keep new ones coming.
How the Left/Right Channel Extractor works
This channel extractor splits a stereo recording into its two sides. Drop a stereo file and export. The left and right channels come out as two separate mono files in a ZIP, named after the original with -left and -right on the end. Choose Left only or Right only to save a single side instead. Preview plays one channel so you can check which is which. Nothing is uploaded.
A stereo file is really two recordings stored side by side, one for each speaker. Most of the time they belong together, but plenty of recorders use them for completely separate sources, and then you need them apart.
When you need to split channels
- Two-person interviews. Many field recorders and USB interfaces put one microphone on the left and the other on the right. Splitting gives each speaker their own track, so you can level, clean and edit them separately before mixing back together.
- Lavalier plus camera mic. Wireless lav receivers plugged into a camera often record the lav on one side and the camera's own mic, or a safety track at lower gain, on the other.
- Dual mono from a mixer. Live desks often send a board feed on one channel and an audience microphone on the other.
- Phone call recordings. Call recorders frequently put the near side on the left and the far side on the right.
- Click track and music. Rehearsal and stage files sometimes carry a metronome on one side and the backing track on the other.
What the channel extractor gives you
Each output file is mono, contains exactly the samples of one channel and has the same sample rate and length as the original, so the two stay perfectly in sync when you line them up in an editor. Nothing is resampled or mixed. Choose WAV to keep every sample untouched, or MP3 for smaller files; a mono MP3 at a given bit rate sounds better than a stereo one at the same rate, because all the bits go to one channel.
Related fixes
If you only want the wrong side moved, or one side copied to both speakers, the Audio Channel Swapper does that in one file. To fold both sides into a single mono track, use Stereo to Mono. To nudge the level of one side rather than remove it, try the Audio Balance and Pan Adjuster.
Tips
- Check which side is which. Preview plays the left channel by default. Switch the Output to Right only and preview again to hear the other side.
- Silent side? If one file comes out silent, the recording really was mono on one channel. The Channel Swapper's "copy to both sides" mode fixes that for playback.
- More than two channels. Only the first two channels of a surround or multitrack file are extracted.
FAQ
Can I split an MP3 into left and right?
Yes. Any format your browser can decode works, including MP3, WAV, M4A, OGG and FLAC. Choose Both to download a ZIP holding a left file and a right file.
Will the two files stay in sync?
Yes. Both files have exactly the same length and start point as the original, so they line up sample for sample when you place them side by side in an editor.
Why is the output mono?
Each file holds one channel. That is what editors expect when you import separate speaker or microphone tracks, and a mono file is half the size of the stereo original.
Is my audio uploaded?
No. The file is decoded, processed and encoded inside your browser with the Web Audio API. Nothing is sent to a server, so it works offline once the page has loaded and your audio stays private.
See also: all Audio tools, Images, Video & Screen, PDF, SVG, Simulations & Screensavers, Generative Art, Chart Makers, 3D Model Viewers, Drawing Pads, Mockups & 3D Making, Diagram Makers, 3D Science, Tracker Music.
Related tools
Audio Channel Swapper
Swap stereo channels, copy one side to both, or invert polarity.
Stereo To Mono
Downmix stereo audio to mono and export it as WAV.
Audio Balance And Pan Adjuster
Shift audio left or right, or pan a mono file into stereo.
Audio Splitter
Split one audio file into equal parts or fixed-length chunks, zipped.
Audio Mixer
Layer several audio files to play together, with clip-safe levels.