Will the output sound any wider than the mono original?

No, and it cannot. Copying one channel to two produces identical channels, which by definition have no difference for a stereo system to place anywhere. The sound sits exactly in the centre, which is what the operation is for.

Why does it refuse a stereo file?

Because there is nothing to convert. A stereo file already has two channels, and the tool's job is the specific conversion from one to two. Refusing makes the situation clear rather than producing output that is identical to the input for reasons that would not be obvious.

Is any quality lost in the conversion?

No. Each sample of the mono channel is copied into both output channels unchanged, so the file contains the same samples as the original with nothing recalculated. The conversion can be repeated or reversed without any accumulation of error.

How do I make a mono recording sound wide?

Not with a straight copy, since there is no difference to scale. Adding a slightly delayed or modulated copy of the signal to one side creates the difference that a stereo image needs, which is what the chorus effect does by design.

Why would I need this at all?

Because some players, editors and delivery pipelines require two channels and will reject or mis-handle a single-channel file. Converting is a compatibility step rather than a processing step, and it leaves the audio exactly as it was.

Mono-to-Stereo Converter

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Stereo-to-Mono Converter

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Enhance stereo field width

Channel Mixer

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Mid-Side Encoder

Encode stereo to Mid/Side format

Mono-to-Stereo Converter turns a single-channel recording into a two-channel file by copying it to both sides. The result sits dead centre, which is exactly what makes it compatible everywhere.

What is Mono-to-Stereo Converter?

Drop a mono file and process it; both output channels are exact copies of the input, and the result downloads as a stereo WAV.

What the tool does:

It requires a single-channel source and refuses a file that is already stereo, rather than silently doing nothing.
Both output channels are the input channel, sample for sample and bit for bit.
The output is written as a stereo WAV, so a player that insists on two channels will accept it.
Nothing in the signal is changed: no gain, no filtering, no delay between the sides.

The value of the tool is in how unremarkable it is, and that is worth stating clearly because it is easy to expect the wrong thing from a converter with this name. Copying one channel to two produces a signal that is by definition identical on both sides, which means it has no side component at all: the mid and side view of the result puts all of the energy in the mid channel and none in the side. The consequence is that the result is perfectly mono compatible, since folding the two channels back together returns exactly the original sample values, and it sits dead centre in the stereo image with no sense of width whatsoever. That is the correct behaviour for the job, which is getting a mono file into a container or a workflow that expects two channels, and it is the wrong thing to reach for if the intent is to make a mono recording sound wide. Because the copy is exact, the operation is reversible by the stereo to mono converter and the round trip returns the original file, and it can be repeated without any degradation, since no processing is applied at any stage and the samples are copied rather than recalculated.

What it cannot do:

No width, because there is nothing for the two channels to differ by.
No delay, panning or level offset between the sides.
No reverb or doubling, which are separate effects.
It refuses a stereo source rather than converting it in some other way.
No change of format beyond writing two channels instead of one.
Output is sixteen bit WAV.

Use it when a mono file has to be delivered in a two-channel container, when a player or a pipeline will not accept a single-channel file, or as a first step before adding a real stereo effect. When the aim is actually to make a mono recording sound wider, the stereo widener cannot help for the reason above and a chorus or a short delay between the channels is the approach that works, and when the question is what happens when a stereo mix is folded to mono, the stereo to mono converter answers it. It is worth stating plainly what the conversion does not do, because the name invites the opposite expectation: a copy of one channel into two creates no difference between the sides, so no amount of listening will reveal any width, and the file will behave identically to the original mono one in every situation except that it satisfies software expecting two channels.

How to use Mono-to-Stereo Converter

Drop a mono file onto the panel; a stereo file is refused with an explanation.
Process it, which copies the single channel to both sides.
Check that the result plays as a stereo file in whatever player you use.
Download the WAV.

When to use Mono-to-Stereo Converter vs related tools

Mono-to-Stereo Converter is the tool for putting a mono recording into a two-channel container without altering it. Stereo-to-Mono Converter performs the opposite fold. When the goal is genuine width rather than compatibility, Stereo Widener scales an existing difference and Chorus Effect adds a delayed copy, both of which create side content where this tool deliberately creates none.

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