So no, there's no end - the field of music theory continues to increase in breadth and depth, and there's probably already too much for any individual to learn comprehensively.
- How long does it take to finish music theory?
- How long does music theory take to learn?
- Is music theory really hard?
- How do you study music theory effectively?
How long does it take to finish music theory?
So how long does it take?!
Bearing in mind all the points above, (and the obvious fact that some people are quick learners and others are less so), in my experience the average time it takes most people to pass ABRSM grades 1-5 music theory is around 3 months per grade.
How long does music theory take to learn?
If you play metal, rock, hardcore, etc. Then you don't need to know that much music theory, only the basics. It will probably take you about 8 months to a year to learn that.
Is music theory really hard?
Music theory is difficult to grasp because it uses visual methods to describe what we hear. That's a big problem for music theorists because our brains interpret music hundreds of times faster than it takes to explain it. This is why music is powerful.
How do you study music theory effectively?
In order to develop fluency with your music theory, so it becomes something you can use rather than a chore you have to do, you need to: Memorize all key signatures. Understand how chords are constructed and where they fit in a key. Be able to instantly name any interval from any root note.