Convert stereo to mono without losing anything to phase
This stereo to mono converter folds the left and right channels of a recording into one. Mono is what podcasts, audiobooks, voice notes, phone systems, smart speakers, single-speaker radios and hearing-aid streaming really need, and a mono MP3 or AAC can use the whole bitrate for one channel — so you get the same clarity in a smaller file.
Mixing two channels together has one trap: if they are out of phase, they cancel. A stereo widener, a reversed microphone cable or some vintage “fake stereo” records can make a mono mix sound thin, hollow or almost silent. Every stereo file you add here is analysed first; if the channels would cancel, the page warns you, shows how much quieter the mix would be, and offers a polarity fix or the option to keep just one channel.
How to use the Stereo to Mono Converter
- Drop your stereo files on the upload area. Each file is decoded and checked for phase problems; an “Out of phase” badge marks any that would cancel.
- Choose how to make mono: mix both channels, or keep only the left or the right channel.
- If a file is flagged, tick Flip the right channel’s polarity before mixing, or keep a single channel instead.
- Keep the original format or use a quick setting such as Podcast · MP3 96 kbps, then press Convert to mono.
- Compare Before and After, and download each mono file or all of them as a ZIP.
Stereo to Mono Converter features
Safe mixdown
Mono = (left + right) ÷ 2, so in-phase material keeps its level and the result can never clip.
Out-of-phase detection
The correlation between the channels and the level lost in a mono mix are measured for every stereo file, and badly phased files are flagged before you convert.
One-click polarity fix
Flipping the right channel before mixing turns cancellation back into a full-strength mono signal.
Keep left or right
When the two sides carry different things — two interview mics, a translation track, a camera’s backup channel — keep just the one you need.
Podcast and voice presets
Quick settings switch to MP3 at 96 kbps for podcasts or 64 kbps for voice notes; or keep the original format and bitrate.
Batch, tags and ZIP
Convert a whole folder; titles, artists and cover art are carried over.
How the phase check works
For each stereo file the tool measures the correlation between left and right, from +1 (identical channels) through 0 (unrelated) to −1 (one channel is the other upside down), and calculates how loud the mono mix will be compared with the stereo original. Normal music sits around +0.3 to +0.9 and loses 0–3 dB, which is expected. When the correlation falls below −0.25 or the mix would lose more than 6 dB, the file gets an “Out of phase” badge and the warning explains what to do.
Flipping the polarity of one channel before mixing turns a correlation of −1 into +1, so the two halves add up instead of cancelling. If only part of a song is out of phase, as with some stereo effects, keeping one channel is often the cleaner option.
Settings for podcasts, phones and voice
For telephone and speech-recognition rates, resample the mono file with the Audio Sample Rate Converter. To trim silence or cut a section first, open it in the Audio Cutter.
| Use | Suggested output | Size per minute |
|---|---|---|
| Podcast episode | Mono MP3, 96 kbps (64 for speech only) | 0.72 MB (0.48 MB) |
| Voice note or memo | Mono MP3 or AAC, 64 kbps | 0.48 MB |
| Audiobook chapter | Mono MP3, 64 kbps | 0.48 MB |
| Phone system, IVR or speech recognition | Mono WAV at 8 or 16 kHz | 0.96 or 1.92 MB |
| Editing or archiving | Mono WAV or FLAC at the original rate | 5.3 MB as 44.1 kHz 16-bit WAV |
Mix or keep one channel?
- Mix both for music and for any recording where both sides carry the same performance.
- Keep left or right when one side is noise, silence or a different source — for example a camera that records an on-board mic on one channel and a wireless mic on the other.
- Need a stereo file again later, such as for a video timeline? The Mono to Stereo Converter puts mono back in both channels.
- Under the hood: Mediabunny (MPL-2.0) decodes, the mix and phase check run in plain JavaScript, and LAME and libavcodec (LGPL), libFLAC and libvorbis (BSD) write MP3, AAC, FLAC and Vorbis.
Stereo to Mono Converter FAQ
How do I convert stereo to mono?
Drop the file on this stereo to mono converter, keep “Mixing both channels” selected and press Convert to mono. The left and right channels are averaged into one channel in the same format as the original.
Why does my mono mix sound thin or disappear?
The channels are out of phase, so they cancel when added. The tool flags such files; tick “Flip the right channel’s polarity” or keep only one channel.
Does converting to mono reduce quality?
You lose the stereo width but none of the tonal quality. Because a mono MP3 spends its whole bitrate on one channel, speech often sounds cleaner at the same bitrate.
Is mono better for podcasts?
Usually, yes. Most podcasts are speech, which is centred anyway, and mono files are half the size at the same quality per channel and play evenly in a single earbud.
Will the file get smaller?
WAV and FLAC files roughly halve in size. For MP3, AAC and other lossy formats the size depends on the bitrate: keep the original bitrate for better quality at the same size, or choose a lower one, such as 64 kbps, to halve it.
Can I keep just the left or right channel?
Yes. Choose “Keeping the left channel” or “Keeping the right channel”. This is the best fix when one side contains only noise or a different microphone.