Figured Bass Alterations

Accidentals Alone

An accidental sign (#, b, or n) written alone beneath a bass note always alters the third above the bass note. Because a triad in root position is assumed by default (5/3), altering the third directly changes it from minor to major, or vice versa, without needing any digits.

Accidentals Beside Numbers

When an accidental appears beside a number (like 6#, b6, or 6/4#), it indicates that the specific interval above the bass note must be altered by a sharp, flat, or natural sign. For example, a 6 below a bass note with a flat symbol beneath it indicates a first-inversion triad with a flattened third above the bass.

Raised Intervals (Slashes & Plus)

A slash mark through a number (such as 6̷, 5̵, 4̵, or 2̵) or a plus sign (+) indicates that this interval above the bass note should be raised a half step. It means the same as a sharp sign beside the number.

Interactive Alterations Explorer

Use the explorer controls below to add accidentals, naturals, slashes, or plus signs to your figured bass notation. Toggle between different bass notes and inversion figures to see and hear how the accidentals dynamically alter the pitch of the upper voices!

Mastering Altered Figured Bass

Accidentals and slashes expand figured bass into a fully chromatic language, allowing composers to modulate, write secondary dominants, and shape intricate modal colors.

Key rules to remember: • Accidental alone: Alters the 3rd above the bass. • Accidental with number: Alters that specific interval. • Slash (/) or plus (+): Raises the interval by a half step.