The numeric part of a musical interval is found by counting each letter name from the first note of the interval to the last note. This may also be thought of as counting each line and space of the staff from one note to the other, including the lines and/or spaces on which the notes of the interval reside.
For example, look at the following interval below. We would like to find the numeric name for the interval from F to D. To find the correct number, we call F “1”, then count up each letter name (line and space) until we get to D.

We can see from counting that F is 6 letter names (or lines and spaces) from D. Therefore, F to D is an interval of a sixth.
Notice that if we start on D and count down to F we still end up with the same interval:

See, we still end up with the interval of a sixth.
Musical Counting!
Let’s practice – for each interval below perform the following steps to find the numeric name:
- Use the interactive Flat staff at the bottom to place whole notes that are needed on each letter name (line and space) within the given interval (hint – don’t forget to start and end on the notes of the interval).
- Count the number of notes that you placed in step one.
- Enter the number for the interval (counted notes from above step) in the Interval box and click the Submit button.