The answer to the question of whether you need to learn any music theory in order to play the piano, the answer is simply yes. Many ads for online apps that can teach you to learn to play the piano will tell you otherwise. Yes I am saying that they are not being completely honest. The truth is that not matter what style, what genre or whether you can read music or not, theory of music is necessary.
When people talk about theory, we often think of complex and detailed information about playing the piano and music in general. It is often not realized that the simple stuff is music theory too.
Knowing what the names of the notes are on a piano is indeed theory and everyone who wants to play the piano should be able to name all of the notes and exactly where to find them on the piano. It doesn’t matter if you read music or you play by ear, you do need to know them. If you don’t know them yet, there is a pattern of just 12 notes that repeat several times across a piano keyboard, so its not as difficult as most people would think.
Being able to identify a basic 4 beat timing in a piece of music is also really useful. If you can learn to identify a triple beat or something a little more obscure, then it is a bonus.
Knowing the difference between the sound of major and minor is important and then going beyond that and being able to understand the difference between what makes something major and what makes something minor is essential knowledge. There are obviously more scales, or keys that can be learned about, but learning about the difference between major and minor is important.
Sharps and flats are also important to know what they are and even though they have the same ability to change a note, how they do it is completely different. Sharps raise a note, one note (or semitone or half step) higher in pitch (which is to the right on a piano keyboard) while flats lower a note (or semitone or half step) lower in pitch (which is to the left on a piano keyboard).
Knowing what a chord is, is also important. Understanding what a major chord and a minor chord are is the first part step. Understanding other types of chords is very useful, no matter whether you are into modern piano, jazz or classical piano. Its also useful for people who don’t read music because they play by ear.
Music theory is important, no matter the genre and not matter whether you can read music or not. Every bit of knowledge that you get about playing the piano can come under the category of theory.
So don’t be convinced that it is hard or boring – embrace learning as much as you want. It truly doesn’t have to be hard or impossible, especially if you learn a little at a time.
As far as learning theory goes when you are an absolute beginner, you do need to learn some but it doesn’t have to be complex and/or overwhelming.
Even though some learn to play the piano online websites say that you don’t need theory because its too hard or too boring, they still teach it. Just like traditional classical piano teachers, they give you enough theory so you can start playing pieces of music as quickly as possible.