A Guide to Jazz Theory

Have you always wanted to play jazz? Has it always seemed a little intimidating?

Yes, jazz can be quite complex, but with just a bit of basic theory, you can start playing jazz in a matter of minutes! 

This guide is a high-level introduction to jazz theory and covers basic concepts like chords, chord progressions, and scales. For a more in-depth lesson and to hear examples of how these concepts are played with an instrument, be sure to check out this jazz theory class from Martin Cohen.

What Is Jazz Theory?

If you think of jazz as a language, then jazz theory is the vocabulary and grammar rules you need to know in order to speak it. Knowing what chords, scales, and patterns to play will enable you to better understand the songs you’re learning, as well as to improvise your own compositions. 

Types of Jazz Music

There are over 40 different types of jazz music. As the genre evolved over time, it’s been influenced by various musicians, their geographical locations, and other music they listened to, diverging into distinct sub-genres. A few prominent ones include smooth jazz, contemporary jazz, free jazz, bebop, and jazz-funk. Though they all have their own characteristics and distinguishing features, they all follow the same jazz theory basics. 

Can You Play Jazz Without Knowing Theory?

Yes, you can absolutely play jazz just by reading sheet music or learning songs by ear. However, knowing even just a little bit of jazz theory will make a massive difference in your jazz learning journey. Sheet music will be easier to play, learning by ear will be faster, and you’ll even be able to improvise alongside other jazz musicians. 

The Basics of Jazz Theory

Please note that this guide is meant for students who already have a basic knowledge of music theory—ideally, you should already know the different notes, intervals, chords, what it means to play in a certain key, and how to read sheet music. 

Let’s dive in!

Chords

Jazz chords are a distinguishing characteristic of jazz music—they are unique and highly recognizable. 

Most genres of music use triads—three note chords built with a root note, a major or minor 3rd, and a 5th. Jazz chords, on the other hand, typically use at least four notes and include a 7th interval. 

Here are five kinds of 7th chords you can build (though 90% of jazz music uses only the first three). For example, to build a dominant 7th chord, you’d start with the root note, add a major 3rd, perfect 5th, and a minor 7th. 

Now, 7th chords are definitely popular in jazz music, but it doesn’t stop there—we can also add on 9th, 11th, and even 13th intervals. These are called chord extensions. 

To find these extensions, count out the 9th, 11th, and 13th intervals from your root note, following the major scale (even if your 7th chord isn’t major). You can also use intervals like ♭9, ♯9, ♯11, and ♭13 to create altered chord extensions. 

Chord Progressions

A chord progression is a sequence of chords played in a particular order. It’s noted using roman numerals, with each number referring to a corresponding note in the scale. For example, in the key of C major, the number II would refer to the chord D minor 7th because D is the second note in the C major scale. 

The most popular chord progression in jazz is the II-V-I progression. In the key of C major, this progression would translate to the chords Dm7-G7-Cmaj7. 

Other popular jazz chord progressions include the I-VI-II-V, III-VI-II-V, and I-II-III-IV. You’ll also hear plenty of two-chord progressions, such as II-V, V-I, and I-IV. 

Scales and Modes

What are Scales?

A scale is a collection of notes to choose from when playing a melody. It’s important to know them because certain scales sound good with certain chords and give melodies their unique character. 

Scales differ from each other in the size and pattern of intervals between notes. The easiest scale to understand is the major scale, which follows the interval pattern of W–W–H–W–W–W–H (W meaning whole-step and H meaning half-step). You’ll recognize this pattern if you play the C major scale: C-D-E-F-G-A-B-C. 

What are Modes?

Each scale has seven modes—slight variations on the original scale. For example, you could play the C scale with the notes C-D-E-F-G-A-B-C or you could add a variation and play it with the notes C-D-E-F-G-A-B♭-C. The latter is the C scale in a different mode. 

The seven modes are: Ionian, Dorian, Phrygian, Lydian, Mixolydian, Aeolian, and Locrian. Now, it’s important to remember these modes in order from 1-7. You can use a simple mnemonic to help you, such as “I Don’t Particularly Like Modes A Lot”. 

So what mode did we play in when we played C-D-E-F-G-A-B♭-C? First, figure out which key has those exact notes—that would be F major. As a scale, you would typically play it like this: F-G-A-B♭-C-D-E-F. C is the fifth note in the F major scale. The fifth mode is Mixolydian, so what we played was the C Mixolydian scale.

Now, say you want to know how to play the F Dorian scale. Dorian is the second mode, so we ask: what’s a major scale where F is the second note? E♭ major. Now take the notes of the E♭ major scale (E♭-F-G-A♭-B♭-C-D-E♭) and play them in an order that starts and ends with F: F-G-A♭-B♭-C-D-E♭-F. That’s F Dorian.  

Now that you know the different modes, how do you know which chords to play them with? Simply take the 1st, 3rd, 5th, and 7th note in the scale and there’s your chord. Take E Phrygian for example: E-F-G-A-B-C-D-E. The notes E-G-B-D create the Em7 chord. 

Similarly, you can work backwards to find what scale to play alongside a chord you already know. Simply take the notes in your chord, place them in the 1st, 3rd, 5th, and 7th positions in a scale, and fill in the gaps by adding a whole tone to each of these notes. For example, say you want to know what scale to play with the chord Cmaj7. Start with the notes you already know: C-?-E-?-G-?-B. Then go up a whole tone from each of those notes to fill in the gaps: C-D-E-F♯-G-A-B. What you end up with is the C Lydian scale. 

Other Scales

So far, we’ve looked at just the major scale. There are many other scales and each of them have their own modes. Some popular jazz scales include the natural minor, harmonic minor, melodic minor, pentatonic, blues, and bebop scales. 

Resources: What You'll Learn In a Jazz Theory Course

Remember that this guide only scratches the surface of jazz theory—if you’re looking to really start playing and improvising jazz, Martin Cohen’s jazz theory class provides over three hours of in-depth instruction. It covers each of the popular jazz scales mentioned above in great detail, every possible chord and chord progression you can create, and how to put the two together to learn the classics and improvise your own jazz music. 

Ready to Start Playing Jazz?

The Complete Jazz Theory Course - Jazz Chords/Scales and More

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Jazz Theory Books

If you’re looking for more resources on how to learn jazz theory, books are a great option. Be sure to check out: 

• “Jazzology: The Encyclopedia of Jazz Theory for All Musicians” by Robert Rawlins and Nor Eddine Bahha
• “The Jazz Harmony Book” by David Berkman
• “The Jazz Theory Book” by Mark Levine 

Jazz theory is, of course, best learned through audio and video instruction, but these books have been considered staples in learning jazz theory and will help you deepen your knowledge and understanding well beyond the beginner level. Just be sure to have your instrument by your side and try out everything you’re learning right away.

Written By

Sayana Lam

Sayana is a musician, writer and graphic designer based in Toronto, Canada.

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