Lesson 11: Inverting Intervals

In the previous lesson you learned how to write intervals, and how to identify given intervals. In this lesson, you will learn how to invert them.

To invert an interval simply means to "flip it". In other words, once an interval has been inverted, the note that used to be on the bottom is now on the top. The note that used to be on the top is now on the bottom. As you can see, this is not going to be a difficult lesson!

Consider this interval:   It's the one we started with in the previous lesson. As you know, it's called a perfect 5th because counting up from the lower note until we reach the upper note results in the number '5'. And the answer to "Is the upper note in the major scale of the bottom note?" is "Yes", meaning perfect. If this is all still foggy to you, you should review Lesson 10.

Now to invert it. The process is simple: whatever used to be on the bottom becomes the top. So depending on if you moved the lower note up an octave, or the upper note down an octave, you get one of these:

  

Both of the examples above have a 'D' on the bottom and a 'G' on the top, and so there are two correct, acceptable answers.

When you invert an interval, the name of the interval must change. You can go through the exact same procedure that you used to name intervals in the previous lesson: count upward from bottom to top: that gives us a '4'. "Is the upper note in the major scale for the bottom note?" Yes, there is a 'G' in a D-major scale, so the answer is "Perfect 4th". But there's an easier way to name inverted intervals, if you know the name of the original interval. Check out the following table:

Notice that when you invert an interval, simply take the original interval, subtract it from 9, and you'll get it's inversion. For example, If you want to invert a 6th, subtract it from 9 and the answer is a 3rd. (9-6=3)*.

It's tables like this that can make you sound like a genius! It's so easy to learn and commit to memory that you can say to your friends, "Name an interval, and I'll name its inversion it in two seconds or less". They say, "Diminished 6th", and you immediately reply "Augmented 3rd!" No problem!