FourThirtyTwo

How to convert music to 432 Hz on iPhone and iPad

FourThirtyTwo retunes a song from the standard A = 440 Hz to A = 432 Hz, or any pitch from 300 to 600 Hz, and saves a new copy on your device. These are the complete steps, with screenshots from the app converting a real file.

Updated September 30, 2026 · 6-minute read · iPhone and iPad

Quick steps

  1. Tap Import from Files and choose a song.
  2. Check the source tuning. The app assumes 440 Hz. Tap it to run Auto-detect.
  3. Leave the target at 432 Hz, press play and compare Original and Retuned.
  4. Tap Create 432 Hz File.
  5. Tap Add to Library, or Export to save it to Files.

Before you start

  • FourThirtyTwo on an iPhone or iPad running iOS or iPadOS 18 or later. The steps are the same on both.
  • An audio file you can open. MP3, M4A/AAC, WAV, AIFF, CAF and FLAC all work, up to 500 MB per file. It can be in the Files app (On My iPhone, iCloud Drive or another location) or a downloaded, non-DRM song in your Music library.
  • Not Apple Music streams. Apple Music subscription tracks are copy-protected (DRM), and iOS doesn’t let any app change them. Songs you bought DRM-free, your own recordings and ordinary audio files are fine.

Step by step

  1. Import a track

    On the home screen, tap Import from Files. To use a downloaded song from your Music library, tap Import from Music instead. To convert several songs at once, see batch converting.

    FourThirtyTwo home screen with Import from Files, Import from Music and Batch Import buttons, a Library button and an empty mini player

  2. Pick the file

    The standard iOS file picker opens. Browse to your song (here On My iPhone › Sample Sessions) and tap it.

    FourThirtyTwo reads the file where it is. Your original stays exactly as it was, and the app writes a separate retuned copy.

    iOS Files picker showing the Sample Sessions folder with five audio files: Copper Morning, Lanternfield, Paper Orchard, Quiet Meridian and Slow Tide

  3. Check the source and target tuning

    The convert screen shows the track’s waveform and two frequencies. On the left is the source, labelled Assumed 440.00 Hz because every import starts from the standard A = 440 Hz. On the right is the Target, 432.00 Hz.

    If you’re not sure the recording really is at 440 Hz, tap the source value and choose Auto-detect. Here’s why that matters.

    Convert screen for the track Lanternfield: Assumed 440.00 Hz, arrow, Target 432.00 Hz, a Preview Before Converting card with the track’s waveform and play controls, and a Create 432 Hz File button

  4. Preview before you convert

    Press play, then switch between Original and Retuned while the music plays. Only the pitch changes. The song keeps playing from the same spot. Use the scrubber or the 15-second skip buttons to jump around. There’s more on this in comparing 432 Hz and 440 Hz.

    Preview card during playback at 0:11 with Retuned selected, the playhead part-way through the waveform, and a pause button

  5. Create the 432 Hz file

    Tap Create 432 Hz File. For a typical song this takes seconds, and all the processing happens on the device. When it’s done you’ll see Conversion Complete with the file’s details. Here that’s 432 Hz, M4A, 256 kbps, which is the default output format. You can change the default in Settings.

    Conversion Complete screen showing chips for 432 Hz, M4A and 256 kbps, the track name Lanternfield, and buttons for Add to Library, Export and Back to Home

  6. Keep it or export it

    Tap Add to Library to keep the track in the app’s Library, where you can play it and edit its title and artist. Tap Export to choose MP3, M4A AAC, lossless ALAC, FLAC or WAV and Save to Files or Share…. The new file is named after the original with the target added, for example Lanternfield (432 Hz). See exporting as FLAC, ALAC or MP3.

What “converting to 432 Hz” actually does

Converting doesn’t swap out individual notes. It lowers every frequency in the recording by the same ratio, 432 ÷ 440 ≈ 0.982. In musical terms that’s 31.8 cents lower, about a third of a semitone. FourThirtyTwo uses phase-vocoder pitch shifting, so the tempo and length don’t change. It’s the same performance at a slightly lower pitch.

We checked this on the file from the steps above, comparing the original MP3 with the FLAC that FourThirtyTwo exported:

Frequency spectrum around A4. The original file peaks at 439.9 Hz and the FourThirtyTwo export peaks at 431.9 Hz, the same shape moved down by about 8 Hz. Frequency spectrum around A4. The original file peaks at 439.9 Hz and the FourThirtyTwo export peaks at 431.9 Hz, the same shape moved down by about 8 Hz.
The A4 note in the held final chord moved from 439.9 Hz to 431.9 Hz. Across the whole file the measured shift was −31.5 cents, against −31.8 cents expected. The source reads 439.9 rather than 440.0 because the demo’s pad sound is deliberately detuned a touch for warmth.
Show the measured values
Measured from the original MP3 and the FLAC that FourThirtyTwo exported (held A-minor chord, 61.7–67.3 s).
MeasurementOriginalFourThirtyTwo export
A4 peak frequency439.9 Hz431.9 Hz
Overall pitch change (whole file)n/a−31.5 cents (expected −31.8 cents)
Length2,998,800 samples (1:08.000)2,998,800 samples (1:08.000)
Loudness over time for the original (top, mirrored) and the export (bottom). Every section, including the pause at 30 seconds and the final chord at 62 seconds, lines up exactly. Loudness over time for the original (top, mirrored) and the export (bottom). Every section, including the pause at 30 seconds and the final chord at 62 seconds, lines up exactly.
Loudness over time for the original (top) and the retuned export (bottom). Every section, the pause at 30 s and the final chord line up, and both files are exactly 2,998,800 samples (1:08.000) long.
Show the measured values
Loudness envelopes compared in 50 ms windows.
Timing offset between the two envelopes0 ms
Envelope correlation (1.0 = identical shape)0.997
Length, original → export1:08.000 → 1:08.000

About the audio in these screenshots. The tracks (“Lanternfield”, “Quiet Meridian” and friends by “Demo Ensemble”) are short original pieces synthesized for these guides and saved as ordinary MP3, M4A, WAV and FLAC files. They’re part of our tuning test set, which you can download. Everything else is real: the app imported them through the normal Files picker, analyzed and converted them on the device, and the charts are measured from the exact files it exported.

Good to know

  • 432 Hz is a preference, not a fix. Some listeners like how music sounds a little lower. Others hear little difference. FourThirtyTwo doesn’t claim any health or other benefits. It just makes the conversion easy and accurate.
  • Other targets work too. Presets cover 415, 432, 440, 444 and 528 Hz, and you can enter any custom value from 300 to 600 Hz. If a change is bigger than one semitone, the app asks you to confirm first. You can turn that off in Settings.
  • Private and offline. There’s no account and no upload. Import, analysis, preview and conversion all run on your iPhone or iPad.

Try it on your own music

FourThirtyTwo is a one-time purchase for iPhone and iPad. No subscription, no account, and your audio never leaves your device.

Requires iOS or iPadOS 18 or later.