Solfeggio Frequencies Explained: 396, 417, 528, 639, 741 & 852 Hz

PurrHz Guides · Updated November 2026 · 6 min read

The short versionThe Solfeggio frequencies are a set of tones that became popular through 1990s wellness books. They're often called “ancient,” but the numbers come from modern numerology. Many people enjoy them for meditation and relaxation. Just treat the claimed benefits as tradition, not established science.

The original six (and the add-ons)

The core set is 396, 417, 528, 639, 741 and 852 Hz. Three more, 174, 285 and 963 Hz, were added later and often appear in “9 Solfeggio frequencies” playlists.

Real history vs. popular story

The real part: the singing syllables ut-re-mi-fa-sol-la were created in the 11th century by the monk Guido d'Arezzo, who took them from the opening syllables of a Latin hymn to help singers learn melodies. That system became the do-re-mi we still use.

The modern part: the specific frequencies have nothing to do with Guido. They were worked out in the 1970s by Joseph Puleo through numerological patterns in verse numbers from the Bible's Book of Numbers, and later popularized by Leonard Horowitz's 1998 book Healing Codes for the Biological Apocalypse. Medieval singers had no way to measure hertz, and pitch wasn't standardized until the 20th century.

What each frequency is said to do

These are the meanings commonly given in wellness and meditation communities, presented here as tradition, not findings:

FrequencyCommonly described as
396 HzLetting go of fear and guilt
417 HzFacilitating change, clearing the past
528 HzTransformation; the “love frequency”
639 HzConnection, harmony in relationships
741 HzExpression, problem-solving
852 HzIntuition, returning to spiritual order

What science says

Very little research exists. The best-known study tested only 528 Hz: a nine-person experiment that found lower stress markers after listening to 528 Hz–tuned piano music (details here). We aren't aware of controlled studies on 639 or 852 Hz specifically. Fact-checkers have found no evidence for claims such as detoxing the body or repairing DNA.

What is well established is that calm, slow music and focused listening can help people relax. That's a fine reason to use these frequencies, as long as they don't replace real care when you need it.

How PurrHz handles 639 Hz and 852 Hz

Unlike 528 Hz, these two don't sit near a note in standard tuning, so a song can't simply be “in” 639 Hz. PurrHz finds the closest note and shifts the whole track until that note lands exactly on your target:

Both shifts stay under half a semitone, so songs still sound like themselves, just a touch brighter.

Try it: convert a song to 639 Hz, free and private 🐾

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