The space between any two pitches is called an interval. Whole steps and half steps are two types of intervals. A whole step can also be called a major 2nd, and half steps are sometimes called minor 2nds. Major simply means BIG; minor means little. The number 2 (2nd) comes from counting the number of letters from one note to another. Bigger intervals can also be identified by their interval count (or size) and quality (major, minor, etc.).
When counting, always start on 1 (never zero). For example, the interval count from D to B is a 6th:
D (1) – E (2) – F (3) – G (4) – A (5) – B (6)
Instead of counting letter names, you can also count the number of lines and spaces on the staff (still starting with 1). The answer should be the same. By the way, a count of 1 is called a unison or a prime, and a count of 8 is called an octave (instead of an 8th). Also, when counting, it doesn't matter whether or not there are any sharps or flats. D# to B is also 6th; so is D to Bb, or Db to B#, and so on. The differences between these various kinds of 6ths is called the interval quality. You might think of them as different flavors of 6ths.
As another example, A to C has the same interval count as A to C#: they are both 3rds. However A to C# is a BIGGER 3rd than A to C, so they have different interval qualities. Not surprisingly, the BIG 3rd is called a major third and the little 3rd is called a minor third (just like with major and minor 2nds). Unfortunately, there is more than just major and minor. Other interval qualities include perfect, augmented, and diminished.
Finding the interval count is easy enough, but how do you figure out what the interval quality is supposed to be? The simplest way is to go back to the major scale. Taking the intervals from the starting note (Do) to each successive scale degree we get the following intervals:
From Do to ä
|Perfect 1st||Major 2nd||Major 3rd||Perfect 4th||Perfect 5th||Major 6th||Major 7th||Perfect 8th|
Notice that the second, third, sixth, and seventh are all major intervals. (That is why it is called a major scale.) The unison, fourth, fifth, and octave are all perfect. You can find out why they are these qualities another day, but for now just remember:
In a major scale:
- 1,4, 5, and 8 are always Perfect
- 2, 3, 6, and 7 are always Major
(There is NEVER such a thing as a Major 5th or a Perfect 3rd.)
So, to figure out the interval between two notes:
1.) Pretend that the bottom note is the first note (Do) of a major scale. (Write out the scale if you need to or finger it on your instrument.)
2.) Is the top note already in the scale? If yes, then you already know what the interval is. Just count up the number of notes and add the name of the quality (either major or perfect).
- Let's try the interval from G up to E. The G major scale is: G A B C D E F# G
- E is in the scale. It is the 6th scale degree.
- The 6th scale degree is always major.
- G to E is a Major 6th.
3.) If the exact note is not in the scale, you will need to adjust the interval quality. If your note is a half step lower than the major interval in the scale, the quality will be minor. For example:
- Let's try the interval from D up to F. The D major scale is: D E F# G A B C# D
- D to F# is a major 3rd. F is a half step lower.
- D to F is a Minor 3rdFor other qualities, use the following adjustment chart starting from either a perfect or major interval:
|- 2 Half Steps||- Half Step||+ Half|
- Let's try the interval from F to B. The F major scale is: F G A Bb C D E F
- F to Bb is a perfect 4th. B is a half step higher.
- F to B is an Augmented 4th.
What if I can't make a major scale using the bottom note? No problem, you can use the same method of adjusting the quality in reverse.
- Let's try the interval from C# to E. I don't like C# major, so I'll spell a C major scale instead.
- The C major scale is: C D E F G A B C. C to E is a major 3rd. C# to E will shrink the size by a half step.
- C# to E is a minor 3rd.