Musician's Phrasebook
Flat Intervals (b3, b7...)
The “b” in front of a number means one fret lower than the major version of that interval. A b3 is one fret below the major 3rd, a b7 is one fret below the major 7th — the number tells you which interval, the b tells you it's been flattened.
Why it matters
A b3 is what makes a scale sound minor instead of major, and a b7 is what gives blues and dominant chords their pull. Once you know “b” just means “one fret flatter,” every scale formula on this site reads like a sentence instead of a code.
Used in a sentence
“The blues scale is the minor pentatonic with a b5 added — that's the blue note.”
See it on the fretboard →
← Back to the full glossary
New to guitar? Start here →