Free tools for your next audio edit
Mono to stereo converter. Put one channel on both sides.
Turn a short mono MP3 or WAV into a two-channel PCM WAV with the same signal on the left and right. Preview and download locally, without an account or upload.
Convert mono to dual-mono stereo
Free · localAudio is decoded and prepared in your browser. Decoding resamples to 48 kHz; WAV output is 16-bit PCM and does not preserve tags or artwork. Keep your original.
One source, two matching channels
How to convert mono audio to stereo
- 01 / SOURCE
Choose a mono file
Select a supported mono MP3 or WAV up to five minutes and 50 MiB. The tool checks the decoded channel count; it rejects an existing stereo file rather than silently mixing it.
- 02 / PREVIEW
Compare the prepared WAV
The browser copies the decoded signal to matching left and right channels. Listen to the prepared file and compare it with the original before saving.
- 03 / VERIFY
Download and check the layout
Save the two-channel 48 kHz, 16-bit PCM WAV. Open it in the WAV inspector to check stored channel count and format. Keep the original.
What the conversion does
Dual mono is a stereo file with identical channels
A mono file has one channel. This converter writes that channel twice, producing a two-channel file with matching left and right samples in the PCM output. It can help when a destination requires a two-channel file or when a mono source needs to feed both sides of a stereo track. It does not create the differences between channels that convey spatial width.
Duplicating a mono voice does not isolate it from music or background noise already in the same recording. If a recording has two different channels, use the channel splitter to inspect them instead. The mono versus stereo guide compares channel layouts and playback.
The output is a new PCM16 WAV decoded at 48 kHz, not a bit-for-bit copy of the input. Resampling, quantization and clipping may change samples, and MP3 decoding cannot restore discarded information. Tags and artwork are not copied.
File size and handoff
Check the output size before using it
Two-channel PCM stores twice as many channel samples as mono PCM at the same sample rate and bit depth. At 48 kHz and 16 bits, the audio payload is 192,000 bytes per second, before the WAV header. The output must fit 50 MiB as well as the input; a file can pass the input check and still be too long for this WAV export.
The audio file size calculator estimates a PCM export and compares limits. To shorten a supported source first, use the audio trimmer, then choose the saved excerpt here. Confirm that its beginning and end contain the context needed for your edit.
A few useful answers
Free mono to stereo converter questions
How do I convert mono to stereo?
Choose a supported mono MP3 or WAV. The converter decodes it, copies the same signal to left and right, and prepares a two-channel WAV to preview and download.
Does dual mono create stereo width?
No. The channels are identical. A two-channel file may satisfy a channel-layout requirement but it does not reconstruct spatial information that was not in the mono recording.
What files and limits are supported?
Choose a mono MP3 or WAV up to five minutes and 50 MiB. The prepared two-channel WAV must also fit 50 MiB, so some inputs need to be shortened first. Browser codec support varies.
Is the output lossless?
The output is 48 kHz, 16-bit PCM WAV. Decoding, resampling, quantization and clipping can change samples; an MP3 source has already undergone lossy compression. Tags and artwork are not preserved.
Does this separate voice from music?
No. It copies the complete mono mix into two channels. Source isolation is a different workflow and does not recover original session tracks.
After preparing your audio