What is Mono to Stereo Converter?

Turn mono audio into stereo using duplicate, widen (with an adjustable width), pseudo-stereo, or pan modes, then collapse stereo files back to mono whenever you need to.

Accepts MP3, WAV, OGG, FLAC, AAC, M4A, and WebM up to 50 MB. Widen mode adds a Haas-style delay of a few milliseconds between channels, which the ear interprets as spatial depth without sounding obviously echoed. Pseudo mode uses complementary comb filtering to create a wider perceived image that still sums correctly to mono. Pan mode shifts a single source left or right with constant-power gain. To Mono mode is offered automatically when you load a stereo file and need to collapse it back to a single channel. Output can be exported as 16-bit PCM WAV, MP3 at 128/192/320 kbps, or lossless FLAC, ready for any DAW or distribution platform.

How to use

1. Upload a mono audio file in WAV, MP3, OGG, or FLAC format.
2. Choose a mode: Duplicate (same audio on both channels), Widen (subtle inter-channel delay), Pseudo (comb-filtered width), Pan (place the source in the stereo field), or To Mono (collapse a stereo file back to one channel).
3. Pick an output format (WAV, MP3, or FLAC), preview the result, then download the converted file.

When to use

• Spread a mono voice recording to feel more present in headphones.
• Convert a mono podcast feed for platforms that require stereo files.
• Pan an instrument track to a specific side before mixing it into a song.

Result

A podcaster uploads a mono voice recording, turns on widen mode for a touch of spatial depth, and the result sounds more natural through headphones.

FAQ

What's the difference between duplicate and widen mode?

Duplicate sends an identical copy to left and right channels. The result is technically stereo but sounds the same as mono. Widen adds a small inter-channel delay so the brain perceives width, useful for voice or single instruments.

Will widen mode introduce noticeable echo?

Not at the default 15 ms. The Haas precedence effect makes the ear read short delays (the slider tops out at 30 ms) as depth rather than echo. If any spread feels like too much, the Stereo Width slider blends the effect back toward mono.

Can I undo the conversion and get the original mono back?

Yes. The export is always the converted file, so your original is untouched. If you need a mono file from a stereo source, sum the left and right channels in a separate audio editor.

What output formats can I download?

WAV, MP3, or FLAC. WAV is lossless 16-bit PCM at the source sample rate, ideal for further editing in a DAW. MP3 ships at your chosen bitrate (128, 192, or 320 kbps) so it is small enough to upload straight to podcast hosts or social platforms. FLAC is lossless like WAV but typically half the size, useful for archival.

Will the file size double when going from mono to stereo?

WAV doubles when going from mono to stereo because two channels need twice the bytes. If size matters, pick MP3 in the format selector — stereo MP3 at 192 kbps is roughly 1.4 MB per minute. FLAC sits between the two: lossless like WAV but compressed.

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