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
Digging deeper
On the A string, C is a b3 above A — one fret below C#, which would be the major 3rd. Learn that one relationship and every “b” symbol on this site clicks into place.
Not to be confused with: Don't confuse flattening a note (playing it one fret lower on the neck) with a flat interval symbol (b3, b7) in a scale formula — they describe the same fret-distance idea, just in different contexts: an action versus a label.
Common questions
Is a b3 always the same as a minor third?
Yes — “b3” and “minor third” are two names for the exact same interval, three semitones above the root.
Why don't all intervals get a flat version?
Only intervals with a “major” version to begin with (2nd, 3rd, 6th, 7th) get a flat form written this way. The root, 4th, and 5th are called “perfect” and use different terms (augmented/diminished) when altered.
New to this? Start beyond tabs →