First off if you are going to learn piano by ear using chords you need to learn your scales. Scales on the piano is the actual foundation to playing the piano with chords. Because chords are made up of those scales. Like the notes in the scale is going to tell you what chords you need to be playing when you are playing a song.
Scales form chords so you need to understand them and practice them. Find a good place that will teach you the formula for scales and how to form them. You can have access to this information for free, try to find free videos but also something that is going to write and tell you how to form them. Its is very simple you just need to practice scales in all 12 keys.
The second tip to learn to play piano by chords is to start to learn how to form chords. After you learn scales it is very easy to figure out how to form chords using the scale. There is 2 main chords you should learn how to form, and there are 2 secondary chords you should learn. If you are just starting the last two you shouldn’t worry to much about because you really need to master the first to. The 4 are first major.
Major are the primary number one chords. They are the main chords that all other chords lead to.
Second is Minor these are used very often but are more like passing chords to get to your final destination, which is the major.
The third is diminished, These chords are based off the 7th tone of a scale. And they are not used as much, it is more for when you get advanced and you can use them to add alot of flavor to your piano playing.
The fourth chord is the augmented and I don’t use this to much. It is not totally necessary to know but it is a good tool to throw in if you want.
Need help figuring out piano chord? Check out our awesome piano chord chart.