All About 3rds

3rds go with 5ths.

The 3rd is the second most important interval in music. In fact, 3rds work together with 5ths to make major and minor chords, which are the foundation of almost all popular music and also the backbone of traditional music. Without 3rds we have no music, for the most part. 3rds are also important in aug and dim chords, but less so because there are alternate spellings for these other chords

These are the intervals we need. Anything else is rare and in almost all cases not needed:

  • 3 or M3
  • b3 or m3
  • bb3 or dim3, which in chord notation is assumed to be 2 and never marked

View or Download All About 3rds


3 thoughts on “All About 3rds

  1. I especially liked the fact that the PDF on thirds begins with the harmonic minor scale and the augmented second it contains, which is the enharmonic equivalent to the minor third. There are many books and sites out there on theory. It would not be useful to have yet another one saying the same thing. Most are abstract, not connecting to music. The aug2 is presented late as an “advanced” thing. Yet students learn early on to play the harmonic minor scale, and it occurs often in music. They are left wondering as they see a 2nd on the page, but hear a 3rd as they play it, and see the same spacing in the piano keys as with some thirds. Why not demystify this early, as you have done here.

  2. I found the black 6 sided stars today in Wingdings, a font I’ve used for maybe 20 years. I was looking for something to highlight things that are all black on the piano. I navigate by color and sound. I’m just explaining now what I see for myself. So I now have a template for all the other intervals. 🙂

  3. The visual page showing 3rds has given me a better understanding of the concepts involved. It’s logical, taking one step at a time. The stars and arrows are quite helpful.


Leave a Reply