How can you play by ear if you don't have perfect pitch, you don't have sheet music, you don't even have a chord chart?!
It IS possible! Developing your ear is a skill that takes time to learn, but because it's a skill that means you CAN learn it.
I have been working on it for pretty much my whole life, and in that time I've picked up a few tips that can make the process faster and easier.
We're going to use the song "Photograph" by Ed Sheeran as our example song today. I don't have the music, I don't have a chord chart. I just have my ear.
So let's go!
Figure out what key the song is in
Knowing the key will help us figure out the chords, melody notes and chord progression so much faster. It can be a challenge to find the key, because songs don't always start (or end) on the root note.
A good way to start is to figure out the last note of the chorus. A LOT of the time that note makes up one of the notes in the root chord -- which will reveal the key.
Next, we need to figure out the chord progression
This is actually not as hard as you might think. If you're trying to find a pop chord progression, there is a VERY good chance the song will use one of the most common progressions in pop music.
The best one to start with is the 1-5-6-4 progression. Knowing this progression provides a really good place to start figuring out which chords the song uses.
Once you know those common chords, you can start singing along and identifying which of those 4 chords comes next. Remember, the 1-5-6-4 progression is a guide -- and songs don't always use those chords in that order (although many do).
This process can take a while, so be patient
I'm not going to lie. It can take a while to go through a song and figure it out. It is a skill that takes time to develop. I can do it pretty well because I have played so many songs. I play songs every day -- it's my job!
The more you play, the more you will get an instinct and an ear for this. Remember it's a skill (have I said that enough?) and like any skill, you need to practice it to get better.
A good way to practice away from the piano is to listen to songs that you know and try to 'hear' the chord changes. Try to identify what a 1-5-6-4 progression sounds like in a song. Listen to a 1-6-5-4 progression. Listen to songs while following a chord chart so you can hear what chord progressions sound like.
Finally, if you really don't want to sing...
I know I talk about singing a lot here, and it is such a useful way to help you pick out the song. But if you really don't want to sing, you can still learn to play by ear. Just work on picking the melody out first. You can do that by listening to the song (on repeat) and figuring out the melody notes.
Even humming to yourself can be really helpful. Once you know the melody, it's easier to start matching chords using the progression method I talked about before, or by using the melody notes to identify the chords. We have a great lesson on that here.
My final piece of advice is to start with an easy song that you already know quite well. Don't jump into a complicated tune that has key changes and weird chords. Start simple and build your skills from there.
And as always, have fun!