Can you use demi(e) and moitié interchangeably

Question

j'ai mangé la moitié du chocolat j'ai mangé un demi-chocolat

Accepted Answer

Bonjour Diana !

In most cases meaning "half", "demi(e)" and "une/la moitié de" are equivalent.
Une demie-baguette / la moitié d'une baguette

However, "demi(e)" refers more to a characteristic of the object (it's a half-thing) rather than a quantity as such.
So in the case of chocolate, you only say "un demi-chocolat" if you actually ate a half (piece of) chocolate, but if you refer to half a given quantity of chocolate, then it will be "la moitié du chocolat" :)

I hope that's helpful!
À bientôt !

Answer

In other words, one could eat half of a smaller baguette: I could say "J'ai achete une demi-baguette mais j'ai mange la moitié de la demi-baguette"?  (Sorry, I don't know how to type the accents). "Demi-baguette" is the name of the item; "la moitie" is the amount I ate, n'est-ce pas?