1 1/16 inches. It's slighly bigger than a quarter, but smaller than a 1976 Jefferson half dollar. The outer rim sports the same ridged pattern as a quater.
Oh, you have got to hear the story about where this thing came from. (My mom got it from my dad. I was wrong about that.)
My dad found it 25 years ago. He was working on a Toyota car. (Don't know the model.) He was replacing the carpet, wich was factory and hadn't ever been replaced. When he was pulling up the carpet in the driver floorboard, it was under the carpet, tucked into a small recess, and taped down.
He said it was inside a hard plastic case, which was inside a plastic bag. Also included was a piece of paper with the same type of writing as the coin. He says it wasn't a replica of what is printed on the coin, but seemed to be in the same language.
I don't care if this thing is worthless, I'm still enjoying the *&^^ out of this.