How do you determine the difference between a minor interval and a diminished interval?

Question

This is for both triads and specific intervals ranging from seconds to sevenths -- I don't understand how to decipher if an interval is a minor, major, diminished, augmented, etc. I thought I had an idea but I feel like there may be special exceptions?

Answer 1

Hi Jax,

I think it's important we first get our terminology straight. A "minor interval" isn't a common term, but you might be referring to all the minor intervals (minor 2nd, minor 7th, minor 13th, etc.). Same thing with diminished (diminished 5th or 7th). When talking about intervals, major, minor, diminished, augmented and perfect are modifiers of the interval. For 2nds, 3rds, 6ths and 7ths, we use minor and major, with major always being one half step above the respective minor interval. So a minor 6th (m6) is 8 half steps while a major 6ths (M6) is nine half steps. For 4ths, 5ths and unisons (or octaves), we use perfect to describe how that interval is in the major scale. If it's a half step below that perfect interval, we use diminished and if a half step above, we use augmented. For example, an augmented 5th is enharmonically equivalent is a m6. This diminished/augmented system can be applied to 2nds, 3rds, 6ths and 7ths as well. Commonly, in jazz harmony we will have an augmented 2nd (or 9th) which is equal to a m3. We can even have double diminished or double augmented intervals, although these are rarely used in real music.

For determining whether an interval is a m6 or an augmented 5th, it depends on context. If we already have a 5th, it's safe to say we have a m6. The same thing can be said if it's a minor chord without a 5th. An augmented 5th is generally part of a major chord, thus having a major third. These sound quite different despite being the "same interval."

For chords, the same words (minor, major, diminished, augmented) are used to refer to related triads. An augmented chord has a major third and augmented 5th while a diminished chord has a minor third and diminished 5th. For diminished chords, we also have half diminished and fully diminished seventh chords which add a minor 7th (10 half steps from root) or diminished 7th (9 half steps from root) respectively.

Hope this helps and please let me know if you have other questions :)

Answer 2

I think it helps to consider this in the context of the key you are working in. Only then do you have the fixed scale degrees that define the intervals. Otherwise, you are free to write the notes enharmonically, which will change the scale degree of the interval. A diminished interval is 1 semitone lower than the corresponding minor or perfect interval. Within a key, inverting a minor interval yields a major interval, and inverting a diminished interval yields an augmented interval. Augmented intervals are 1 semitone higher than the corresponding major or perfect interval.

Answer 3

What a great question. But, I am not sure you actually got a written answer you were specifically looking for. So, let's break it down with a simple, reliable method that has no "special exceptions."

Identifying an Interval

Let's start at the beginning. To identify any interval, you just need to answer two questions:

1. What is its number? (like 3rd, 5th, 7th)
2. What is its quality? (like Major, Minor, Perfect)

A Simple Two-Step Method

Step 1: Find the Interval Number (The Easy Part)

This is the simplest part—just count the letters from the starting note to the ending note, including the start itself. It doesn't matter if the notes are sharp or flat for this step.

1. Example: From C to A, you count C(1), D(2), E(3), F(4), G(5), A(6). So, any kind of C to any kind of A will always be a 6th. Each step MUST have a unique letter -- this may seem obvious, but sometimes it'll get weird (double diminished 4th for example), so remember this golden rule.

Step 2: Find the Interval Quality (The Ruler Method)

The trick to finding the quality is to use the Major scale of the bottom note as your perfect measuring stick. 📏 Every note in a major scale gives you an interval from the root that is either Major or Perfect.

There are two "families" of intervals that come directly from the Major scale:

1. Perfect Intervals: The 1st (unison), 4th, 5th, and 8th (octave).
2. Major Intervals: The 2nd, 3rd, 6th, and 7th.

Once you know the "ruler" interval from the Major scale, you can find all other qualities by altering it by one half-step (one fret on the guitar):

1. If an interval is one half-step smaller than Major, it becomes Minor.
2. If an interval is one half-step smaller than Perfect (or Minor), it becomes Diminished.
3. If an interval is one half-step larger than Major or Perfect, it becomes Augmented.

Putting It All Together (Examples)

Let's identify the interval from D to F:

1. Number: Count the letters: D(1), E(2), F(3). It's a 3rd.
2. Quality: Think of the D Major scale. The third note of the D Major scale is F♯. Our note is F natural, which is one half-step smaller than the Major 3rd (F♯). An interval one half-step smaller than Major is Minor.
3. Answer: D to F is a Minor 3rd.

Let's identify the interval from C to G♭:

1. Number: Count the letters: C(1), D(2), E(3), F(4), G(5). It's a 5th.
2. Quality: Think of the C Major scale. The fifth note is G. This is a Perfect 5th. Our note is G♭, which is one half-step smaller than the Perfect 5th (G). An interval one half-step smaller than Perfect is Diminished.
3. Answer: C to G♭ is a Diminished 5th.

How This Connects to Chords

This is where it all comes together! Chords are just intervals stacked on top of each other. A triad, the most basic chord, is simply two 3rds stacked up.

1. Major Triad: A Major 3rd + a Minor 3rd. (e.g., C-E-G)
2. Minor Triad: A Minor 3rd + a Major 3rd. (e.g., C-E♭-G)
3. Diminished Triad: Two stacked Minor 3rds. (e.g., C-E♭-G♭)
4. Augmented Triad: Two stacked Major 3rds. (e.g., C-E-G♯)

By understanding intervals first, you can now build or identify any chord you see. 👍

Answer 4

Answer 5

Minor chords vs diminished chords. A Minor chord is build with a minor 3rd (4 1/2 steps) then a major 3rd (5 1/2 steps) ACE or

A A# B C C# D D# E (with sharps) usually spelling in music for A minor

A Bb B C Db D Eb E (with flats)

A Diminished chords is build with all minor thirds (4 1/2 steps) ACEb or

A A# B C C# D D# E (with sharps)

A Bb B C Db D Eb E (with flats) usual spelling in music for A diminished

Answer 6

A major interval is two whole steps from the note of origin. A minor interval is the distance from one note to the next note that is 1 and a half steps above it, for instance in a C scale that might be the distance from C to Eb. A diminished interval would be a half step down, the distance from C to bbE or C to D which may be enharmonic to a major 2nd. Another example would be a diminished 7th which would be a bb7 or a flatted dominant 7th, equivalent to major 6th. You may also have a perfect 4th or 5th diminished by flatting them one half step.