Does converting stereo to mono lose quality?

The sound itself keeps its quality: the sample rate stays the same and a WAV stays lossless. What you lose is the left-right placement, which matters for music mixed wide and hardly at all for speech. An MP3 is re-encoded, so pick 128 kbps or more for music.

Which channel has my voice?

Drop the file and look at the two level meters: the side with the voice shows a much higher level. When one side is more than 20 dB quieter than the other, the page marks the loud side as suggested. You can also play the file and switch between the modes to listen.

What if my file is already mono?

The page says so and you can still save it as MP3 or WAV, for example to change the format. If a stereo file has the same sound on both sides, it tells you that too; converting it halves the size of a WAV without changing the sound.

Which files does it take?

MP3, M4A, AAC, WAV, OGG, OPUS, FLAC, WEBM and MP4 files up to 100 MB and 30 minutes, saved as MP3 or 16-bit WAV at the original sample rate. The whole file is decoded in your browser's memory, which is why there is a limit; split a longer file with the Audio Trimmer first.

No. The file is processed in your browser and is not uploaded: the page decodes it, mixes it and writes the new file on your device. The page records ordinary analytics events, such as the mode and format you chose, not the file or its name.

Stereo to Mono Converter

Mix a stereo recording down to mono, or keep only the left or right channel when the voice is in one ear, and download it as MP3 or WAV. The page shows how loud each side is and warns you when the two sides would cancel. Everything runs in your browser; the file is not uploaded.

Drop your stereo file here or click to browse

MP3, M4A, AAC, WAV, OGG, OPUS, FLAC, WEBM or MP4, up to 100 MB and 30 minutes.

The file is processed in your browser and is not uploaded.

How to convert stereo to mono

Three steps, in your browser.

1
Drop the file
A song, an interview or a voice memo: MP3, M4A, WAV, FLAC and other common formats up to 100 MB and 30 minutes. The page measures both sides and shows their levels.
2
Mix both sides or keep one
Mix both sides for music and for recordings with sound on both sides. If the voice is only in one ear, keep that side; the page suggests it when one side is nearly silent. Press play and switch between Original and Mono to hear the difference.
3
Convert and download
The result is one channel at the original sample rate, saved as an MP3 at the bitrate you choose or as a 16-bit WAV. Normalize (on by default) sets the loudest moment to -1 dB so the mono file is not quieter than it needs to be.

Only changing the format? MP3 to WAV and AAC to MP3 have a mono switch too; this page is for choosing the channel.

What the stereo to mono converter does

Mixes both sides
Each mono sample is the average of the left and the right sample. An average can never be louder than the louder side, so the mix cannot clip; sound that sat on one side only ends up 6 dB quieter, which Normalize makes up.
Keeps one side
A lavalier or interview microphone plugged into a stereo recorder often puts the voice in one ear and silence or hiss in the other. Keeping the side with the voice gives you a clean mono track at full level instead of a quieter mix with the other side's noise.
Shows each side's level
Two meters show the average and the peak level of the left and the right side, so you can see at a glance which side holds the voice before you choose.
Warns when the sides cancel
If the two sides are nearly opposite, for example when one microphone was wired the other way round, adding them cancels much of the sound. The page spots this and tells you to keep one side instead.

When mono helps

A voice in one ear
An interview recorded with one microphone into a stereo input plays in one ear only. Keep that side and it plays in both ears on any headphones or speaker.
Mono speakers and one-ear listening
Some speakers play only one channel, and people who hear with one ear or listen with one earbud miss whatever is only on the other side. A mono file sounds the same everywhere.
A podcast or voice track
Speech rarely needs stereo. A mono voice track is simpler to edit and level, and the voice sits in the middle on every device.
A smaller file
A mono WAV is half the size of a stereo one. For MP3 the size is set by the bitrate, so a mono MP3 at a lower bitrate can sound as good as a stereo one at a higher bitrate.

Recording interviews: how to record an interview, interview recording apps and journalist recording devices.

Stereo or mono: file size for one minute

Computed for one minute of audio:

Format	Stereo	Mono
WAV, 44.1 kHz, 16-bit	10.1 MB	5.0 MB
WAV, 48 kHz, 16-bit	11.0 MB	5.5 MB
MP3, 128 kbps	938 KB	938 KB

An MP3's size is set by its bitrate, not by the number of channels; at the same bitrate a mono MP3 spends all of it on one channel.

Mix or keep one side?

Mix both sides when there is sound worth keeping on both: music, a room recording, a stereo podcast with one person on each side. The mix keeps everything, centred.

Keep one side when the other side has nothing useful: silence, hiss or a second microphone that picked up only the room. The meters above the options show which side that is, and the page suggests it when one side is more than 20 dB quieter.

If the file is already mono, or both sides carry identical sound, the page says so. Converting it still gives you a smaller WAV or a plain MP3.

When the recording is an interview or a call

A voice stuck in one ear usually comes from an interview or a call recorded with one microphone. When what you need is what was said, ParrotNotes records the conversation on your phone and gives you the transcript and a summary, free for 100 minutes of recording a month.

Get ParrotNotes free

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