G♭5 — 739.989 Hz

G♭5 and F♯5 — Enharmonic Equivalents

G♭5 and F♯5 are enharmonic equivalents — they sound identical at 739.989 Hz but are written differently depending on the musical context.

When to Write G♭5

G♭ is the tonic of G♭ major (6 flats) and is the enharmonic twin of F♯ major. G♭ major is the only major key with 6 flats.

Composers choose G♭ when writing in flat-side keys (D♭ major, G♭ major). In descending chromatic passages within flat keys, G♭ is the theoretically correct spelling. G♭ major and F♯ major sound identical but use different notation; the choice depends on the surrounding harmonic context.

G♭5 in Instrument Literature

Wind and brass ensembles occasionally encounter G♭ in heavily flatted keys. Harpists may prefer G♭ major over F♯ major because harp pedal notation maps more naturally to flats. Flute players in orchestral literature sometimes see G♭ in modulating passages.

In fixed-do solfège, G♭ is sung as "se" (♭5). In G♭ major with moveable do, it is "do" (the tonic).

How F♯5 Differs in Context

While F♯5 sounds identical to G♭5, it belongs to a different set of keys and carries different harmonic implications.

F♯ is extremely common for string instruments — violinists encounter it in G major (1 sharp), their most natural key after C. Guitarists play F♯ regularly in keys like G, D, and E major. Keyboard players see it as the first sharp in the key-signature order.

Enharmonic equivalents share the same frequency in equal temperament. In historical temperaments like Pythagorean or meantone, they may differ slightly — see the temperament comparison table above for this note's exact deviations.