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Convert stereo video audio to mono

Preview stereo and mono, choose the source, then export.

How it works

ImportChoose source
EditSet the change
PreviewReview result
ExportCreate file

InputMP4, WebM, MOV and M4V videoOutputMP4 or WebM video

MP4 · WebM · MOV · M4VChoose a videoConvert its stereo audio to mono.

Mono puts identical sound in both channels, which guarantees every listener hears everything regardless of how they are listening. It is the right choice for single-microphone speech, for fixing phase problems, and for anyone whose video will be played on a phone speaker, a single earbud or a mono PA. This tool previews stereo against mono and lets you choose the source.

When mono is genuinely better

A single microphone recording is mono already — presenting it as stereo just means two copies of the same thing with a bit of extra file size. More importantly, true mono is immune to the failure modes stereo has: nothing can be lost when a listener uses one earbud, nothing changes when a venue plays it through a mono system, and no part of the mix vanishes when the channels are summed. For speech-led video, the loss of stereo width costs nothing and the reliability is worth a lot.

Phase cancellation, and which source to use

Summing two channels that are out of phase makes them cancel, and the audible result is a track that goes thin or hollow — sometimes losing a voice almost entirely. That is why the conversion offers a choice: sum both channels, or take one channel and duplicate it. If the summed version sounds noticeably worse than the stereo original, phase is the reason, and using a single channel avoids it completely. Check by ear rather than assuming, since the problem only affects some recordings.

Questions, answered

When should I convert audio to mono?

For single-microphone speech, when phase problems make the stereo mix hollow, and when the video will be played on phone speakers, one earbud or a mono system.

Will I lose anything by converting to mono?

Stereo width and any sense of space. For speech that costs nothing; for music it can matter, so keep a stereo version if the material is musical.

Why does my mono version sound thin or hollow?

Phase cancellation between the two channels. Use a single channel duplicated to both sides instead of summing, which avoids the cancellation entirely.

Should I sum the channels or duplicate one?

Summing preserves everything in both channels and is the default. Duplicate one when the channels are out of phase, or when only one of them holds a usable recording.

Does mono make the file smaller?

Slightly, since one channel of audio is encoded instead of two. The saving is minor compared with the video itself.

Convert stereo video audio to mono

When mono is genuinely better

Phase cancellation, and which source to use

Questions, answered

Useful next steps