How do you say my heart is so happy in french?

There are a few ways to say "My heart is so happy" in French, depending on the nuance you want to convey:

Formal:

* Mon cœur est rempli de joie. (My heart is filled with joy.)

* Je suis très heureux/heureuse. (I am very happy.)

Informal:

* Mon cœur déborde de joie. (My heart overflows with joy.)

* Je suis tellement content/contente. (I am so happy.)

* J'ai le cœur qui chante. (My heart sings.)

* J'ai le sourire aux lèvres. (I have a smile on my face.)

You can also use exclamatory phrases to express even more joy:

* Quel bonheur ! (What happiness!)

* Je suis tellement content/contente ! (I am so happy!)

* C'est merveilleux ! (This is wonderful!)

Choose the phrase that best suits the situation and your level of formality.