The B major blues scale is the sound of the blues with a smile on its face. It is a six-note scale that takes a bright, cheerful scale and adds one gritty "blue" note for attitude. If you've ever heard a country guitarist or a Southern rock player rip off a happy, bouncy lick that still sounds bluesy, you've heard this kind of sound. It's also small and friendly under the fingers, so you can start using it today.
Here are the six notes:
B, C#, D, D#, F#, G#
The first note, B, is the root. That's the home note, the one everything else leans back toward. When you end a lick on B, it sounds finished.
Each note also has a number that describes its distance from the root. Musicians call this the formula:
You might notice something that looks odd: the scale has both a D and a D#. Don't worry, that isn't a mistake. In B, the bright, happy third is D#. The bluesy flat third sits one fret lower, and that note is D. Because the scale uses both the 3rd and the flat 3rd, you get two notes with the same letter name. You could think of D as "the 3rd, pulled down a little". It's spelled this way so the numbers in the formula make sense.
Scales are built from steps. A half step (H) is the distance of one fret. A whole step (W) is two frets. A W+H is a step and a half, which is three frets.
The pattern for the major blues scale is W - H - H - W+H - W - W+H. Start on B and follow it:
Try it on one string. Play the open B string (the 2nd string), then frets 2, 3, 4, 7, 9 and 12. You've just walked the whole scale up a single string, and you can actually see the pattern.
This scale is built from the B major pentatonic scale: B, C#, D#, F#, G#. That five-note scale is sweet, open and cheerful. The major blues scale simply adds one extra note to it: D, the flat 3rd.
That D is the "blue note", and it's the characteristic sound of this scale in this key. On its own, it can sound a little sour against a B major chord. The trick is how you use it. Players rarely sit on it. Instead they slide or bend from D up into D#, so the note sort of sighs its way into the happy major 3rd.
Listen for that little smear from D to D#. That's the moment the scale goes from "pleasant" to "bluesy". It's the same move you hear all over country, Southern rock and jump blues: bright melodies with a bit of dirt on the boots.
One more thing: the G# blues scale uses exactly the same notes. What changes is which note feels like home. Over B chords, B is home and you get the happy sound. Over G# minor chords, G# becomes home and the same notes sound darker.
The chord this scale loves most is B major (B, D#, F#). All three of those notes are in the scale. Add G# and you get B6, a classic sweet, swinging sound that suits this scale perfectly. You'll also find G#m (G#, B, D#) hiding inside these notes.
A great first jam is a simple two-chord vamp:
Record yourself strumming that, or loop it, and noodle over the top. Aim to land on B or D# when the B chord comes around.
When you're ready, try a 12-bar blues in B using B, E and F#. The major blues scale sounds strongest over the B chord. Over the E chord, some notes will rub a little, so use your ears: lean on B, C# and F# there, and save the D-to-D# slide for when you're back on B.
Every scale shape starts from the root, so learn where B lives. On a standard-tuned 6-string guitar:
The 7th fret on the low E string is a comfortable spot to start. Put your finger on that B, then play the scale notes nearby: every B you find is a safe place to start a phrase and a satisfying place to end one. The 2nd fret on the A string gives you a lower, chunkier position that's great for country-style licks around the open strings.
Start small. Play just three notes: D, D#, then B. Slide from D into D# with one finger, then resolve to B. Do it slowly ten times until that little slide feels natural and sounds sweet, not sour. Then put on your B to G#m vamp and make up tiny phrases that end with that move. Five minutes a day of this, and the happy blues will start coming out of your hands on its own.
For the bigger picture, read The Major Blues Scale.