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Figured bass is a notational shorthand originating in Baroque music, placing Arabic numerals below a bass note to indicate the intervals (and thus the chord) built above it. A 6 below a bass note indicates a first-inversion chord (6/3), while 6/4 indicates second inversion. Accidentals in the figures modify the implied intervals. The system guided keyboard continuo players who improvised chords from a bass line, and it remains central to the analysis and notation of voice-leading in academic harmony study.
Practice reading figured bass by playing the bass note in the left hand and identifying which intervals to add in the right. Work from Bach continuo parts or textbook exercises, realizing short passages before attempting full chorales. Cross-reference with Roman numeral analysis to see how both systems describe the same harmony from different perspectives.
From your prerequisites in chord inversions and interval basics, you understand that a triad can appear in root position (root in the bass), first inversion (third in the bass), or second inversion (fifth in the bass), and you can measure intervals by counting staff steps. Figured bass is a notational shorthand that combines these two concepts: Arabic numerals written below a bass note indicate the intervals — measured upward from that bass note — that form the chord to be played above it. This system originated in Baroque keyboard practice, where continuo players (typically harpsichordists or organists) improvised chords from a single bass line annotated with figures.
The core convention is simple. An unfigured bass note (no numbers) means a root-position triad: you build a 5th and a 3rd above the bass (the full figure would be 5/3, but it is left implicit). A 6 below a bass note indicates first inversion (6/3, abbreviated to just 6): the chord contains a 6th and a 3rd above the bass. A 6/4 indicates second inversion: a 6th and a 4th above the bass, with the fifth of the chord sitting in the bass. For seventh chords, 7 indicates root position (7/5/3), 6/5 indicates first inversion, 4/3 indicates second inversion, and 4/2 (or just 2) indicates third inversion. Each figure describes the chord's structure relative to its bass note, not its position in the key — the same figure produces different chords depending on which bass note it appears above.
The conceptual trap is confusing figured bass numbers with scale degrees. Scale degrees are fixed positions in a key (1 is always tonic, 5 is always dominant). Figured bass numbers are intervals measured from the current bass note — they change meaning every time the bass moves. A "6" above E means a 6th above E (C), while a "6" above G means a 6th above G (E). The number "6" does not refer to scale degree 6; it measures a distance. Accidentals in figures modify only the specific interval they accompany: a sharp next to "6" raises the 6th above the bass by a half step, leaving all other intervals unchanged. A slash through a number also indicates raising that interval by a half step.
Figured bass remains central to academic harmony study because it makes voice-leading relationships visible in a way that Roman numeral analysis does not. Roman numerals identify chords by their scale-degree root and quality (I, IV, V7), abstracting away from specific voicing. Figured bass specifies the vertical intervals above the bass, making the actual spacing and inversion audible on the page. A "6" tells you exactly which voice configuration to play; a Roman numeral tells you the chord's harmonic function but not its voicing. Both systems describe the same harmony from different angles, and learning to translate between them — seeing that a "6" on E in C major means a first-inversion C major chord, which Roman numeral analysis labels I6 — is one of the most valuable cross-referencing skills in harmony study.
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