How do I know what key to write in?

Question

I've recently become obsessed with **Les Miserables** and **Miss Saigon**. The music has inspired me tenfold to compose, write similar music. I've posted on here before on how to compose, and I'm trying my best but struggling with something: **When you denote the time signature, you also have to say what key it is in, right? For example: A Minor etc... but how do you know what key it is in exactly? It is the first note you play; does that become the key it is in?** I know what I want it to sound like. I have a vision in my head, but I wouldn't (at this stage) know what 'key' it is in. I am a beginner, but very determined and would appreciate some help.

Answer 1

Hi there, I'm glad that these two musicals have been inspiring to you and have started you down a new musical journey! It sounds like you have some questions about time signatures and keys, right? You are correct to say that at the beginning of a piece, generally the composer will indicate the time signature and the key of the piece. As far as knowing what key you want to write in, and how to tell what key a piece is in, things get a little more subjective. Here's my advice:

What a key really tells you in a piece of music is which note, or which chord is "tonic". The tonic is the note or chord that people say sounds like "home". What chord does your song end on? That's generally a good indicator of what key it's in. What note or chord do you keep coming back to? Which one, when you land on it, feels steady and secure? That's your tonic. I can explain much more theory than this, but this is the simplest description I can give for now. Please reach out if you want more clarification, I'm happy to help!