Form
A themeB A♭ major, then a C pedalA′ theme, variedB B unchangedA″ theme, varied againC più mosso, climbing by fifthsA‴ theme, four barsCoda triplet runs, then F major
Bars 1–4 in F minor
Sections
A (1–16): the theme
F minor and A♭ major alternate, each with its own dominant, so E♭ (V/III) in bar 1 resolves to A♭ in bar 2. ♭II in bar 6 and V lead back to i in bar 8, and the repeat ends on an Italian sixth in bar 16.
B (17–24): A♭ major, then a C pedal
Bars 17–18 cadence in A♭, and bars 18–20 repeat the move a third higher. Chopin's bass holds C, the dominant, through bars 20–24 while the edition prints the chord roots, and a German sixth, D♭ F A♭ B, lands on C in bar 23.
C (48–72): più mosso
Cadences climb by fifths, F minor at bar 49, C minor at 52, G minor at 56, and bars 57–64 set a new tune in F minor then B♭ minor. Over Chopin's D♭ bass in bars 65–69 a common-tone diminished seventh slides into the German sixth, and bars 71–72 move one chord a beat, D♭⁷, B♭⁷, E⁷, A⁷, back to V⁷.
Coda (77–101): F major
Triplet runs play over Chopin's march bass through bars 77–84, one A natural in bar 89 makes the tonic major, and bars 98–99 confirm it with B♭ minor, iv borrowed from F minor, then C⁷ and F major.
Study edition
Partial analysis: opening bars and a short note on each section. The full breakdown of every section is in the study edition of Nocturne in F minor.
Where it sits among the other twenty is in the nocturnes ranked by difficulty, the method for learning it from these chords is in how to memorize a Chopin nocturne, harmony first, and the left-hand pattern under it is measured in Chopin’s left-hand patterns, ranked by stretch.